Refuse to vote, putting Jack on the spot (7)
I believe the answer is:
abstain
'refuse to vote' is the definition.
(I've seen this before)
'jack on the spot' is the wordplay.
'jack' becomes 'ab'.
'on' says to put letters next to each other.
'the spot' becomes 'stain' ('stain' can be a synonym of 'spot'**).
'ab'+'stain'='ABSTAIN'
'putting' acts as a link.
(Other definitions for abstain that I've seen before include "Deny oneself" , "Cut it out!" , "Don't vote" , "go on wagon" , "Go without" .)