Is the extra “your” supposed to be there?
No. Sorry about that.
Knock yourself out examining the dreidel (5,4,3,3)
Going over the top?
Affirmative.
'Twas the time of the many works of Victor Vasarely. (5)
Should the length be (2, 3) as in OP ART?
Nope, one word, five letters. But you are on the right track!
Opera (op + era)?
Correct. (Opera is also the plural of opus = many works.)
Stone falling into the sea doesn’t much matter (1,4,2,3,5)
A DROP IN THE OCEAN (double definition)
Often twisted in bank ledger (5)
ANKLE (hidden word)
Substitute Phosphorous for Nitrogen and remove Oxygen from turtle to make a cat. (7)
Substitute Phosphorous for Nitrogen and remove Oxygen from turtle to make a cat. (7)
LEOPARD (Leonardo, with P replacing N and minus O)
+++++
Nefarious bad boy went on British television show (7,5)
Downton Abbey (anagram)
+++++
(From the Oracle) “If the Childe of Destinie you’d see/In the coombe yon cenotaph holds the key.” (7)
BEYONCE (hidden word)
Hey pinhead, specify how you inserted that femur backwards. (8)
Cenobite (C + bone (backwards) + ite)
++++
Virtually running to a wedding? (5)
ELOPE (e-lope)
Game benefit includes huge time. (9)
Game benefit includes huge time. (9)
OPERATION [Op(era)tion]
+++++
A hen whimpers mournfully where ambitious politicians go. (3, 9)
New Hampshire (a hen whimpers)
++++++++++++
Replace second wheel? (6)
Would the answer be “retire”?