A very enjoyable start to the day – thanks Basilisk!
As ever, a very witty and well thought out crossword with a good range of clues. If you’ve spotted a Nina or theme, let me know in the comments. (Basilisk usually includes something extra, but I’ve not spotted it).

ACROSS
1. Prime minister did as well as possible in reversing split (6)
DECAMP
(PM (Prime Minister) + ACED (did as well as possible))< (<in reversing)
4. Degree opens up ways of comparing masses of material? (8)
BALANCES
BA (degree) + LANCES (opens up)
10. Less sophisticated company behind opening of restaurant (7)
COARSER
CO (company) + ARSE (behind) + R[estaurant] (opening of)
11. Work in stone of woman holding child (7)
MASONRY
MARY (woman) holding SON (child)
12. They produce wool and milk reportedly (4)
EWES
“USE” (milk, “reportedly”)
13. Tailors costumes around lives? (10)
CUSTOMISES
(COSTUMES)* (*tailors) around IS (lives) &lit
16. Two seconds encapsulating recording that’s essential to listener (6)
STAPES
S + S (two seconds) encapsulating TAPE (recording)
17. Worry fresh restriction’s not introduced (7)
PERTURB
PERT (fresh) + [c]URB (restriction, not introduced)
20. Understanding seen in entertainment when repeated (7)
ENTENTE
ENT (entertainment) when repeated: i.e. ENT + ENT + E…
21. Vigorously attack case for effeminate facial hair (6)
GOATEE
GO AT (vigorously attack) + E[ffeminat]E (case for)
24. Banality is represented in a way that cries out for more? (10)
INSATIABLY
(BANALITY IS)* (*represented)
25. Advance payment needed having separated from divorced wife and daughter (4)
ANTE
[w]ANTE[d] (needed, having separated from W (wife) and D(daughter), divorced (i.e. not together))
27. Express dissatisfaction with card player’s punishment (7)
BOOKING
BOO (express dissatisfaction) + KING (card)
Booking is a caution / yellow card in football
29. Cutting response connected with current job cuts (7)
RIPOSTE
RE (connected with), I (current) + POST (job) cuts
30. Tree developed tiny nuts forever (8)
ETERNITY
(TREE)* (*developed) + (TINY)* (*nuts)
31. Trustworthy bridesmaid holds cross (6)
HYBRID
[Trustwort]HY BRID[esmaid] (holds)
DOWN
1. Contract passing on introduction of rent charges (8)
DECREASE
DECEASE (passing on), R[ent] (introduction of) charges
2. Women with defensible positions each enlist a criminal (11)
CHATELAINES
(EACH ENLIST A)* (*criminal)
3. I’m indifferent about introduction of social network (4)
MESH
MEH (I’m indifferent) about S[ocial] (introduction of)
5. Let in Grant and Edward (8)
ADMITTED
ADMIT (grant) + TED (Edward)
6. Arrogance is something one takes for granted (10)
ASSUMPTION
7. French city reportedly has sufficient power (3)
CAN
“CANNES” (French city, “reportedly”)
8. Harry Styles is as foxy as can be! (6)
SLYEST
9. EU measure abruptly elevated dispute (5)
ARGUE
(EU + GRA[m] (measure, abruptly))< (<elevated)
14. Surveyor’s vessel protected by small warship (11)
SCRUTINISER
TIN (vessel) protected by (S (small) + CRUISER (warship))
15. Dull person who takes steps to progress (10)
PEDESTRIAN
18. Dull person attracted to the opposite sex (8)
STRAIGHT
19. Red Guards never tortured clergyman (8)
REVEREND
RED guards (NEVER)* (*tortured)
22. Wicked sailor cracks on (6)
VIABLE
VILE (wicked), AB (sailor, able-bodied seaman) cracks
23. Warning of change with temperature dropping (5)
ALERT
ALTER (change, with T (temperature) dropping)
26. Active and lively resistance breaks agent (4)
SPRY
R (resistance) breaks SPY (agent)
28. Prime factors of longer number with no prime factors (3)
ONE
[n]ONE (longer number literally, with no prime factors: both literally and figuratively)
TWO HEADS ARE BETTER THAN ONE!
Thanks, Basilisk and Oriel!
Liked CUSTOMISES, PERTURB, DECREASE, STRAIGHT and REVEREND.
ONE
Prime factors of l-ONgEr (letters no. 2,3 and 5, prime numbers)
Number with no prime factors (not a prime number) ONE
Nina helped. 20a entertainmENT ENTErtainment. I reckon ONE is from the prime positions (2,3,5) in lONgEr.
Crossed again.
Thanks KVa – proving the Nina true!
🙂
I agree with Hovis@4 on ENT+ENTErtainment
The nina greatly helped me complete this so I cant exactly say I did it all my own!
Great puzzle
Thanks Basilisk and Oriel
Saw ENTERTAINMENTENTERTAINMENT and LONGER but missed the inner Nina.
It’s a good place to put one – an outer Nina would usually show more signs of strange constrained words.
Most recently Jack had one like this in the Guardian 29,046 (April 17) and Serpent had one in Independent 11,421 (May 20).
I understand that Basilisk, Jack and Serpent are all the same person. I must remember to be on the ALERT – certainly with this trio,
Once I saw the grid I was expecting to find a Nina in the inner ‘circle’ as it is one of our setter’s favourite places to hide a message
Thanks to Basilisk for the most enjoyable crossword and to Oriel for the blog
Just a thought…
STRAIGHT
Dull & Person attracted…(adj and noun) or
Dull person & attracted…(noun and adj)
Either seems to work.
Thanks for the blog , really good set of clues, STAPES was very neat and STRAIGHT a clever DD.
I like these pfime factor clues , I have seen 2,3,5,7,11 but do not think a setter has got to 13.
Is ONE a number with no prime factors? The current concensus is yes, but historically 1 has been in and out of the primes.
Finished eventually . I agree in the quality of puzzle and blog, so thanks to setter and blogger. I have failed to spot the nina. Please could someone kindly enlighten me?
SM@14
The nina: TWO HEADS ARE BETTER THAN ONE!
It is on the inner periphery.
Thanks Basilisk for an excellent crossword. I was on the lookout for a nina and spotting it helped me solve several clues. I failed with BALANCES and couldn’t parse ONE but all else eventually fell into place. As usual there were many great clues including DECAMP, COARSER, MASONRY, CUSTOMISES, STAPES, INSATIABLY, ETERNITY, HYBRID, and REVEREND. Thanks Oriel for the blog.
Got it . Thank you KVa @15
Many thanks to Oriel for the excellent blog. And thanks to everyone who has taken the time to solve the puzzle and leave a comment.