Scientific study of works claiming most of credit (6)
I believe the answer is:
optics
'scientific study' is the definition.
(I've seen this before)
'works claiming most of credit' is the wordplay.
'works' becomes 'ops' (op is short for opus, a work).
'claiming' indicates putting letters inside.
'most of' means to remove the last letter.
'credit' becomes 'tick' (I've seen this before).
'tick' with its last letter taken off is 'tic'.
'ops' placed around 'tic' is 'OPTICS'.
'of' acts as a link.
(Other definitions for optics that I've seen before include "Science of light" , "Spirit measures" , "Scientific studies of light and vision, the eyes" , "The scientific study of light and vision" , "Devices attached to bottles to measure out spirits" .)