Neck of mutton (5)
I believe the answer is:
scrag
'neck of mutton' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for scrag that I've seen before include "The inferior end of a neck of mutton" , "Lean end of mutton neck" , "End of neck - beat up" , "Poor quality meat - throttle" , "Bony part of the neck" .)