Pattern exciting clients (7)
I believe the answer is:
stencil
'pattern' is the definition.
(thesaurus)
'exciting clients' is the wordplay.
'exciting' indicates an anagram.
'clients' with letters rearranged gives 'STENCIL'.
(Other definitions for stencil that I've seen before include "Clients for copying device" , "Design inked through perforated sheet" , "Model" , "Sheet with cut-out letters, pattern etc for copying" , "Sheet with holes used to make ink or paint patterns" .)