Cartilage in meat (7)
I believe the answer is:
gristle
'cartilage in meat' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for gristle that I've seen before include "Tough flexible tissue" , "Stir leg to get tough tissue in meat" , "It's hard to eat" , "Cartilage in meat" , "Sinew" .)