Back some oddball act accepting sound of disapproval (7)
I believe the answer is:
catcall
'sound of disapproval' is the definition.
(I've seen this in another clue)
'back some oddball act accepting' is the wordplay.
'back' shows that the letters should be reversed in order.
'some' indicates a hidden word (some parts of the word are used).
'llactac' is hidden in the letters of 'oddball act accepting'.
'llactac' backwards is 'CATCALL'.
(Other definitions for catcall that I've seen before include "Barracking" , "Disapproving outcry" , "Jeer" , "taunt from the audience" , "Audience's expression of disapproval" .)