Cooked lamb, say, will be awful (7)
I believe the answer is:
abysmal
'awful' is the definition.
(I've seen this before)
'cooked lamb say' is the wordplay.
'cooked' is an anagram indicator.
'lamb'+'say'='lambsay'
'lambsay' with letters rearranged gives 'ABYSMAL'.
'will be' is the link.
(Other definitions for abysmal that I've seen before include "awful" , "Immeasurably bad" , "Really terrible" , "Unfathomable - extremely bad" , "Dreadful" .)