Withdraw concerning pamphlet (7)
I believe the answer is:
retract
'withdraw' is the definition.
(thesaurus)
'concerning pamphlet' is the wordplay.
'concerning' becomes 're'.
'pamphlet' becomes 'tract' ('tract' can be a synonym of 'pamphlet').
're'+'tract'='RETRACT'
(Other definitions for retract that I've seen before include "Eat one's words" , "Revoke" , "Withdraw one's statement" , "Take back (statement)" , "Sheathe" .)