Apostle's taken with alloy (6)
I believe the answer is:
pewter
'alloy' is the definition.
(I know that pewter is a type of alloy)
'apostle's taken with' is the wordplay.
'apostle' becomes 'Peter' (Peter is an example).
'taken' means one lot of letters goes inside another.
'with' becomes 'w' (short for with).
'peter' going around 'w' is 'PEWTER'.
(Other definitions for pewter that I've seen before include "prize-money" , "Grey alloy of tin and lead, makes mugs etc." , "Tin alloy used in tankards, etc" , "Silver-grey alloy" , "Alloy of tin with copper and antimony" .)