It's lean, child, covered with cheese (7)
I believe the answer is:
stilton
'cheese' is the definition.
(stilton is a cheese)
'it's lean child covered' is the wordplay.
'it's lean' becomes 'tilt' (synonyms).
'child' becomes 'son' (male child).
'covered' means one lot of letters goes inside another.
'tilt' put inside 'son' is 'STILTON'.
'with' acts as a link.
(Other definitions for stilton that I've seen before include "No tilts (anag.)" , "English blue cheese" , "Type of cheese" , "Cheese variety" , "English cheese, usually veined" .)