Provocation (3,3)
(Other definitions for red rag that I've seen before include "Bull incitor?" , "Reputed to annoy bull" , "It is offensive to a bull" , "Gerard (anag) - cause of infuriation" , "Proverbial bull enrager" .)
'provocation' is the definition.
(I know that provocation can be written as incitement)
This is the entire clue.