Men provided something cold for opening (7)
I believe the answer is:
orifice
'for opening' is the definition.
(synonyms)
'men provided something cold' is the wordplay.
'men' becomes 'OR' (military abbreviation for Other Ranks).
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'something cold' becomes 'ice'.
'or'+'if'+'ice'='ORIFICE'
(Other definitions for orifice that I've seen before include "Hole in the head, perhaps?" , "provided by gold and diamonds" , "Vent" , "Bodily hole" , "Hole, opening" .)