Quick cryptic No 903 by Hurley

This took me 12 minutes, with ATTEST and SHAFT being the last ones in.

Across
1  Want some grades – I revised (6)
DESIRE – Hidden in {gra}DES I RE{vised}
4  Bank’s constant warning signal (6)
CAMBER – C{onstant} and AMBER (warning signal)
8  A way to move up valuable ultimately for dancer Fred (7)
ASTAIRE – A (a) STAIR (way to move up) and {valuabl}E (ultimately, i.e. last letter of valuablE).  An alternative parsing might be possible if AIR can be interpreted as ‘move up’ as in to air an idea, in which case, the parsing could be A (a) ST (way, as in street) AIR (move up) and {valuabl}E, although this is a bit tenuous (or airy)
10  Fully developed formal dress?  About right (5)
GROWN – The formal dress is a GOWN about R{ight}
11  Popular Los Angeles women’s 6?  No (2-3)
IN-LAW – Popular gives IN, L{os} A{ngeles} and W{omen’s).  The answer to 6 is ‘blood relative’, and where I grew up at least, an IN-LAW was never supposed to be a blood relative!
12  With no time set to resume, behave badly with drug, then finish (4,3)
SINE DIE – To behave badly is to SIN, E is the drug, and DIE is finish.  SINE DIE is a Latin expression meaning ‘without a day appointed, or when applied to a meeting or other business, indefinitely adjourned’, as in with no time set to resume.
13  I leave guy improperly for American universities (3,6)
IVY LEAGUE – Anagram, clued by ‘improperly’, of [I LEAVE GUY].  IVY LEAGUE refers collectively to eight of the US top (and oldest) universities (Brown, Columbia, Cornell, Dartmouth, Harvard, Princeton, Yale and Pennsylvania).  These institutions tend to be associated with academic excellence, selectivity in admissions, and social elitism, not at all like our own Russell Group.
17  Done with silver, English – too old (7)
OVERAGE – Done with gives ‘OVER’, silver is AG and E{nglish}
19  Pole, quiet, near the back (5)
SHAFT – My LOI, SH gives ‘quiet’ and AFT is near the back
20  Initially take heed observing really nasty plant (5)
THORN – Initially (first letters of) T{ake} H{eed} O{bserving} R{eally} N{asty}
21  Dad’s mother, with it, beginning to enjoy rock (7)
GRANITE – One’s father’s mother would be one’s GRAN, with IT and first letter (beginning to) E{njoy}
22  Old fashioned dance tune I’m playing (6)
MINUET – Anagram of [TUNE I’M] indicated by ‘playing’.  A MINUET was / is a slow graceful dance in triple measure (whatever that means)
23  Smallest number of sheep covered by newspaper (6)
FEWEST – EWES (sheep) covered by (inside) FT (newspaper – the Financial Times)

Down
1 Arrive at station having sketch uncompleted (4,2)
DRAW IN – As a train DRAWs IN (arrives at the station), a sketch is incomplete (i.e. drops the last letter of DRAWIN{g})
2  11 to settle, moving here? (9,4)
SATELLITE TOWN – Anagram (indicated by ‘moving’) of [IN-LAW] (answer to 11a) and [TO SETTLE].  The question mark indicates that there are other places to which one could move.  A SATELLITE TOWN is a kind of feeder town to a larger town or city, rather than being on another celestial body.
3  Track liar shown up over method (7)
RAILWAY – LIAR reversed (shown up) and WAY (method)
5  An element in Bihar go native (5)
ARGON – Hidden in {Bih}AR GO N{ative}.  Bihar incidentally is a state in East India, divided by the Ganges.  I had misremembered it.
6  Ado over billet upset brother, for one (5,8)
BLOOD RELATIVE – Anagram (upset) of [ADO OVER BILLET] to give BLOOD RELATIVE, of which a brother should be a good example, unlike an IN_LAW (see 11a)
7  Soldier is more offensive (6)
RANKER – Type of double definition, the second a bit tongue-in-cheek.  A RANKER is a soldier who has served as a Private, or an officer who has risen from the ranks.  It could also mean ‘more rank’ or more offensive.
9  European daisy, say, good seasonal item (6,3)
EASTER EGG – E{uropean} ASTER (daisy) EG (say) and G{ood}
14  Become angry seeing what bull might do around resort? (2,5)
GO SPARE – A bull might GORE.  Put a SPA (resort?) inside for the slang term for becoming furious or angry
15  In good times, teetotaller’s lowest point (6)
BOTTOM – Teetotaller is TT, inside BOOM (good times)
16  Provide evidence for a tutor’s first examination (6)
ATTEST – A (a) T{utor’s} (first, i.e. first letter of) TEST (examination)
18  Woman pawning item on regular basis (5)
ANNIE – Regular basis indicates alternate letters of {p}A{w}N{i}N{g} I{t}E{m}