Clients provide pattern for duplication (7)
I believe the answer is:
stencil
'pattern for duplication' is the definition.
'stencil' can be an answer for 'pattern' (thesaurus). I am not sure about the 'for duplication' bit.
'clients provide' is the wordplay.
'provide' indicates anagramming the letters.
'clients' with letters rearranged gives 'STENCIL'.
Can you help me to learn more?
(Other definitions for stencil that I've seen before include "Template for pattern" , "It helps get uniform print-out" , "It's perforated for ink or paint to pass through" , "Model" , "Clients (anag)" .)