Aid for a fracture (6)
I believe the answer is:
splint
'aid for a fracture' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for splint that I've seen before include "Stick or straight object to which broken limb is fastened" , "'It's used to immobilise a broken leg, say (6)'" , "It's used to immobilise a broken limb" , "Rigid device supporting a fractured bone" , "Fire-lighting wood; aid to bone setting" .)