Chuck, a supporter (5)
I believe the answer is:
sling
I believe this is a double definition.
'chuck' is the first definition.
(thesaurus)
'a supporter' is the second definition.
(a sling supports an injured arm)
(Other definitions for sling that I've seen before include "Stone-throwing weapon" , "American drink" , "Arm bandage; hurl" , "Injured-arm support" , "attached to a rifle, perhaps" .)