Bishop and knight eating uncooked beef (5)
I believe the answer is:
brawn
'beef' is the definition.
(thesaurus)
'bishop and knight eating uncooked' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'and' says to put letters next to each other.
'knight' becomes 'N' (abbreviation for knight in chess).
'eating' is an insertion indicator.
'uncooked' becomes 'raw' (similar in meaning).
'b'+'n'='bn'
'bn' going around 'raw' is 'BRAWN'.
(Other definitions for brawn that I've seen before include "Pressed cooked meat; strength" , "Beefiness" , "Muscular strength" , "Strength; a jellied loaf" , "Muscle; strength" .)