Wound on arm needed treatment (9)
I believe the answer is:
meandered
'wound' is the definition.
('meander' can be a synonym of 'wind')
'on arm needed treatment' is the wordplay.
'on' says to put letters next to each other.
'treatment' is an anagram indicator (letters treated or processed differently).
'arm' after 'needed' is 'neededarm'.
'neededarm' is an anagram of 'MEANDERED'.
(Other definitions for meandered that I've seen before include "Wandered at random" , "Wandered randomly" , "Named deer who wandered about" , "Wandered around aimlessly" , "Of stream, followed a winding course" .)