Finally help India reassess colonialist history (4)
I believe the answer is:
past
'history' is the definition.
(I've seen this before)
'finally help india reassess colonialist' is the wordplay.
'finally' indicates one should take the final letters.
The last letters of 'help india reassess colonialist' are 'PAST'.
(Other definitions for past that I've seen before include "Days gone by" , "Finished, gone" , "Bygone" , "The time that has elapsed" , "Ended" .)