Clamber about branch (5)
I believe the answer is:
climb
'clamber' is the definition.
(thesaurus)
'about branch' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'branch' becomes 'limb' (I've seen this before).
'c'+'limb'='CLIMB'
(Other definitions for climb that I've seen before include "Scale or clamber" , "Get a rise" , "Ascend - ascent" , "Deadened" , "improve one's social status" .)