Playing tabs in a refrain (7)
I believe the answer is:
abstain
'refrain' is the definition.
('abstain' can be a synonym of 'refrain')
'playing tabs in a' is the wordplay.
'playing' indicates anagramming the letters.
'tabs'+'in'+'a'='tabsina'
'tabsina' is an anagram of 'ABSTAIN'.
(Other definitions for abstain that I've seen before include "Pass" , "Refuse to vote" , "Formally decline to vote" , "Withhold one's vote" , "Desist" .)