Pay for one to claim ace held by both sides (6)
I believe the answer is:
salary
'pay' is the definition.
(I know that pay can be written as salary)
'for one to claim ace held by both sides' is the wordplay.
'for one' becomes 'say' (both can mean 'for example').
'to claim' is an insertion indicator (inserted letters are claimed or taken in).
'ace' becomes 'a' (abbreviation).
'held by' means one lot of letters goes inside another.
'both sides' becomes 'lr' (abbreviation for left and right).
'a' inserted inside 'lr' is 'lar'.
'say' placed around 'lar' is 'SALARY'.
(Other definitions for salary that I've seen before include "Worker's pay" , "Regular earnings" , "(Employee's) pay" , "Annual pay" , "Wages" .)