Guys in hamlet manufactured cheese (9)
I believe the answer is:
emmenthal
'cheese' is the definition.
(Emmenthal is an example)
'guys in hamlet manufactured' is the wordplay.
'guys' becomes 'men' (guy can mean a man).
'in' means one lot of letters goes inside another.
'manufactured' is an anagram indicator.
'hamlet' anagrammed gives 'emthal'.
'men' going within 'emthal' is 'EMMENTHAL'.
(Other definitions for emmenthal that I've seen before include "Swiss cheese with holes" , "Hard Swiss cheese" , "Type of cheese" , "Something cheesy" , "Swiss valley giving its name to a cheese" .)