Carelessly omits a Chinese revolutionary (6)
I believe the answer is:
maoist
'chinese revolutionary' is the definition.
(I've seen this before)
'carelessly omits a' is the wordplay.
'carelessly' indicates an anagram.
'omits'+'a'='omitsa'
'omitsa' with letters rearranged gives 'MAOIST'.
(Other definitions for maoist that I've seen before include "Devotee once of the little red book" , "Chinese-style left-winger" , "Political ideologist" , "Supporter of a previous Chinese leader" , "supporter of old Communist" .)