Somehow eats a kilo of meat! (5)
I believe the answer is:
steak
'meat' is the definition.
(I know that steak is a type of primal cut)
'somehow eats a kilo' is the wordplay.
'somehow' indicates anagramming the letters.
'a kilo' becomes 'k' (phonetic alphabet: alpha, bravo, charlie etc.).
'eats' anagrammed gives 'stea'.
'stea'+'k'='STEAK'
'of' is the link.
(Other definitions for steak that I've seen before include "Getting cut" , "High quality beef" , "Thick slice of meat" , "pale by the sound of it" , "Slice of meat or fish" .)