Chap gets wife an alloy (6)
I believe the answer is:
pewter
'an alloy' is the definition.
(I know that pewter is a type of alloy)
'chap gets wife' is the wordplay.
'chap' becomes 'peter' (Peter is a man's name).
'gets' indicates putting letters inside (gets can mean captures or absorbs).
'wife' becomes 'w' (abbreviation).
'peter' placed around 'w' is 'PEWTER'.
(Other definitions for pewter that I've seen before include "Grey alloy of tin and lead, makes mugs etc." , "Bluish-grey alloy" , "Tin alloy for utensils" , "Alloy used for utensils" , "An alloy of tin with a small amount of other metal" .)