A plethora of anagrams and double definitions from Mara today, my second consecutive blog of a Mara puzzle.  I like the dd at 1d, and the device used to drop letters from 16d, and give clues of the day jointly to them.  1a was FOI.  Hopefully you will all find this one satisfyingly doable.  I don't have an accurate time as busy doing other things, but I feel this was certainly within my target.

Across

7  Sunny city on the French Riviera (4)

NICE – Double definition - nice!.

8  Shape on the page not entirely irregular (8)

HEPTAGON – Anagram (irregular) of [ON THE PAG[e}] (not entirely = drop the last letter of {pag}E from the anagrist).

9  A hybrid sort of clue (6)

ACROSS – A (a) and CROSS (hybrid).

10  Parade trinkets also (6)

TATTOO – TAT (trinkets) TOO (also).

11 Uninteresting place to live (4)

FLAT – Double definition - and Norfolk doesn't fit.

12  Mention a funny name (8)

NOMINATE – Anagram (funny) of [MENTION A].

15  Alarm when the cut finger sprained (8)

FRIGHTEN – Anagram (sprained) of [TH{e} (cut = drop the last letter) FINGER]

17  Cricketer with beer to knock back (4)

SLIP – PILS (beer) reversed (to knock back).  There are some excellent schematic maps of cricket fielding positions that may help our non-cricket-familiar friends, just google 'map of cricket fielding positions'.

18  Nude is strangely finding knickers, say (6)

UNDIES – Anagram (strangely) of [NUDE IS].

21 Racket that has strings attached (6)

FIDDLE – Cryptic hint.

22  Complete reinvention of triangle (8)

INTEGRAL – Anagram (reinvention) of [TRIANGLE].

23 Song in concert, unexceptional (4)

TUNE – Hidden answer (in) {concer}T, UNE{xceptional}.

Down

1  Something sent round (8)

CIRCULAR – Double definition.

2  Again organise seaside town (6)

RESORT – Double definition.

3  Box fastener in wood (8)

CHESTNUT – CHEST (box) and NUT (fastener).

4  Notice spinners turning (4)

SPOT – TOPS (spinners) reversed (turning).

5 Box where sculpture perhaps hidden in deception (6)

CARTON – ART (sculpture perhaps) hidden inside CON (deception).

6 Nuts eaten by buffalo, countless (4)

LOCO – Hidden answer inside (eaten by) {buffa}LO, CO{untless}.

13  Chap, if elderly, having various functions (8)

MANIFOLD – MAN (chap) IF (if) OLD (elderly).

14  Fit girl running round bottom of garden, minor (8)

TRIFLING – Anagram (running round) of [FIT GIRL] and {garde}N (bottom of = last letter).

16  Plane top in Germany, though many lost (6)

GLIDER – LID (top) inside GER{many} (many lost means drop the last 4 letters).

17  Dope fixing a steed (6)

SEDATE – Anagram (fixing) of [A STEED].

19  Not any of it, sister said? (4)

NONE – Homophone, sounds like NUN (sister).

20  European sensing English rather bitter, first of all (4)

SERB – First letters (first of all) of Sensing English Rather Bitter.