British, in a spot, don't vote (7)
I believe the answer is:
abstain
'don't vote' is the definition.
(I've seen this before)
'british in a spot' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'in' is an insertion indicator.
'spot' becomes 'stain' ('stain' can be a synonym of 'spot'**).
'a'+'stain'='astain'
'b' placed into 'astain' is 'ABSTAIN'.
(Other definitions for abstain that I've seen before include "Hold off" , "Refrain (from drink)" , "Keep away from drink" , "Withhold one's vote" , "Give backing to" .)