Voting age (8)
I believe the answer is:
eighteen
'voting age' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eighteen that I've seen before include "Old enough to vote" , "Greens on a golf course?" , "11/2 dozen" , "Age when one may legally buy alcohol in the UK" , "when boy becomes man?" .)