Belief in direct action! (6)
I believe the answer is:
credit
'belief' is the definition.
(thesaurus)
'direct action?' is the wordplay.
'action?' indicates an anagram (I've seen 'action' mean this).
'direct' is an anagram of 'CREDIT'.
'in' acts as a link.
(Other definitions for credit that I've seen before include "Arrangement for deferred payment" , "Good reputation; tick" , "good character" , "Favourable balance - good repute" , "Believe - one side of an account" .)