Mike in laboratory producing meat (4)
I believe the answer is:
lamb
'meat' is the definition.
(lamb is a kind of meat)
'mike in laboratory' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' is an insertion indicator.
'laboratory' becomes 'lab' (synonyms).
'm' going inside 'lab' is 'LAMB'.
'producing' acts as a link.
(Other definitions for lamb that I've seen before include "A follower" , "author?" , "Charles ---, essayist; meek animal" , "Tender sheep meat" , "Agnus Dei - . . . . of God" .)