Hard-to-chew piece of meat (7)
I believe the answer is:
gristle
'hard-to-chew piece of meat' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for gristle that I've seen before include "Stir leg to get tough tissue in meat" , "Glister with animal tissue" , "Stir leg (anag.)" , "Inedible cartilage" , "It's hard to eat" .)