A dependably enjoyable puzzle from Monk this morning.
And a pangram to boot! Little bits of general knowledge required to complete this, but nothing obscure. Many thanks to Monk.

F (fine) slapped on OF (concerning) + BASE (counterfeit)
Double definition
[z]INC A[rrowhead] (fragment of)
(DREAM with SUE)* (*cavorting) + UP (at university)
MY (Monk’s); IOUS (financial promises) hiding STER[n] (severe, mostly)
D[iets] O[ften] S[eem] S[trict] (initially)
Z (unknown) + (DIGITAL MAN)* (*animated) introduced by WALT (Disney)
CAST (appointed as characters) + (ON AD ROLL UP*) (*drunk) with X (times)
Castor and Pollux are the stars that make up Gemini
D (duke) + IKE (general)
SOLD (surrendered for a price) occupied by THRONG* (*milling)
SECOND (flash) + SLIP (escape)
From cricket
(LAV (John) holding I (one))< (<back)
FLEE (speed) + C (Charlie) and E (Ecstasy) the D (died)
(SYNC GET)* (*swimming)
F (loud) + [b]UNNY (rabbit, not the first) to go over HA-HA (ditch)
BATT[y] (Nora) brings up her ultimate (i.e. the letter Y is raised)
Nora Batty is a fictional character from the UK sitcom Last of the Summer Wine; A. S. Byatt a world-renowned British novelist
RUM< (spirit, <upset); S[h]A[m]A[n]i[c] (odd characters among) crowds
P (pressure) on RUSSIA (superpower)
TREAD (step on) + MILL (box, once)
A ‘mill’ is an old term for a boxing match.
I wasn’t sure at first where to go with this – the old TV show ‘The Mill’? Old box mills? But I think I have it now.
SUE< (petition, <raised) surrounding QU (question)
More on the play here if you are interested
(JAM< (stuff, <coming up) on ORALS (exams)) about R (right) + GENE (unit of heredity)
(HE (male) and F (female)) after TOT (baby) + [c]O[u]R[t]E[d] (off and on)
DOUBT (are suspicious about) accepting L[arg]E (extremely) + AC (account)
RESI[gned] (gave up, half) + DUE (owed)
(N (new) + OP (work)) stifled by PLAY* (*foul)
IDEA (plan) + [unrave]L (the last to)
HAVE (bear) + N (northern)
I never expect to finish any of Monk’s, and don’t attempt unless I’m feeling brave, but I almost got there today. 3d was my Waterloo, revealed only after I came here. Neither Batty nor Byatt were known.
I managed DOSS, EQUUS, CASTOR AND POLLUX after a bit of web research. Mill/box didn’t ring any bells (never heard of out of UK?). And ha-ha/ditch was new to me.
So it was hard work, but I almost finished. Maybe next time …
I too find Monk a challenge but today went quite well, although I did use some help.
Liked CASTOR AND POLLUX (which went straight in – one of the few stars I know – and then parsed), MYSTERIOUS, WALTZING MATILDA, FUNNY HA-HA ( first heard of ha-ha in a previous crossword), EQUUS
Thanks Monk and Oriel
I enjoyed this although there were a few I couldn’t parse. I couldn’t wrap my head around 1A, 3D, 14A, 15D and 26A but I enjoyed plenty – Treadmill, Castor and Pollux and Major Generals to name but a few.
Thanks Monk and Oriel.
Held up for a few minutes because I always spell Dike with a Y, but then it clicked . . . There were several write-ins to get things going, especially in the NE. Thanks, Monk and Oriel.
Finished this ridiculously fast, with Byatt the only unknown. Mind you, I only knew MILL as a term for a snuff box, which seems to fit the clue better.
Comment #6
Yes some tricky ones, but eminently solvable. Liked Byatt. Thanks Monk and Oriel. l.
Hovis@5, yes MILL=snuffbox. Thanks for that. It can also mean, as a noun, a boxing match (as Oriel notes) or, as a verb, to box. Both of these pugilistic meanings are tagged in Chambers as old slang so “once” in the clue might indicate that Monk had the verb in mind. Not that it matters in the slightest …