Line in excellent meat product (9)
I believe the answer is:
crackling
'meat product' is the definition.
(crackling is roasted pork skin)
'line in excellent' is the wordplay.
'line' becomes 'l'.
'in' indicates putting letters inside.
'excellent' becomes 'cracking'.
'l' going inside 'cracking' is 'CRACKLING'.
(Other definitions for crackling that I've seen before include "Pork covering" , "Crisp exterior of roast pork" , "Crisp skin of pork joint" .)