Keep away - it's a ban (7)
I believe the answer is:
abstain
'keep' is the definition.
(thesaurus)
'away it's a ban' is the wordplay.
'away' indicates anagramming the letters (letters move away from their original places).
'its'+'a'+'ban'='itsaban'
'itsaban' is an anagram of 'ABSTAIN'.
(Other definitions for abstain that I've seen before include "Refuse to vote" , "Resist" , "Choose not to consume" , "Give backing to" , "Choose not to do something" .)