Clamber around branch (5)
I believe the answer is:
climb
'clamber' is the definition.
(thesaurus)
'around branch' is the wordplay.
'around' 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 "Move upwards, ascend" , "Soar" , "Ascend - ascent" , "Scale or clamber" , "Ascend, scale" .)