Commercial retrospective repeatedly displaying nihilistic art (4)
I believe the answer is:
dada
'nihilistic art' is the definition.
'commercial retrospective repeatedly' is the wordplay.
'commercial' becomes 'ad' (abbreviation for advertisement).
'retrospective' says the letters should be written backwards.
'repeatedly' shows that letters should be duplicated.
'ad' reversed gives 'da'.
'da' doubled is 'DADA'.
'displaying' acts as a link.
(Other definitions for dada that I've seen before include "Man Ray's art movement" , "Post-WWI anarchic movement" , "Nihilistic 20th-century European art movement" , "Art concept" , "modern artistic movement" .)