Perhaps copper worker is after material (8)
I believe the answer is:
sergeant
'perhaps copper' is the definition.
'sergeant' can be an answer for 'copper' (I've seen this before). I'm unsure of the 'perhaps' bit.
'worker is after material' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'is after' means one lot of letters go next to another.
'material' becomes 'serge' (type of fabric).
'ant' put after 'serge' is 'SERGEANT'.
Can you help me to learn more?
(Other definitions for sergeant that I've seen before include "military man" , "NCO or police officer ..." , "Pepper, say" , "officer of the law" , "Estrange (anag)" .)