Firm support for unoriginal performer? (6)
I believe the answer is:
copier
'unoriginal performer?' is the definition.
(someone who copies someone else)
'firm support' is the wordplay.
'firm' becomes 'co' (a firm is a company).
'support' becomes 'pier' (type of structure).
'co'+'pier'='COPIER'
'for' acts as a link.
(Other definitions for copier that I've seen before include "Machine for making duplicates" , "piece of office equipment" , "Machine to reproduce print" , "Duplicator" , "Reproducer" .)