Climbing around branch (4)
I believe the answer is:
limb
'branch' is the definition.
(I know that branch can be written as limb)
'climbing around' is the wordplay.
'around' says the answer is hidden in the clue.
'LIMB' can be found hidden inside 'climbing'.
(Other definitions for limb that I've seen before include "Substantial branch from a tree trunk" , "Eg, arm, leg" , "Tentacle" , "Branch - member" , "as part of plane, say" .)