Strange metal boxes people used for cheese (8)
I believe the answer is:
emmental
'cheese' is the definition.
(I've seen this before)
'strange metal boxes people' is the wordplay.
'strange' indicates an anagram.
'boxes' is an insertion indicator (the outside letters must 'box' inside letters in).
'people' becomes 'men' (man is a kind of person).
'metal' anagrammed gives 'emtal'.
'emtal' placed around 'men' is 'EMMENTAL'.
'used for' acts as a link.
(Other definitions for emmental that I've seen before include "Swiss 8 across" , "Holy swiss cheese" , "Gruyere-like cheese" , "Something served on board" , "Swiss food" .)