Specialist in reverse - revolutionary (5)

I believe the answer is:

niche

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'specialist' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.

'in reverse revolutionary' is the wordplay.
'reverse' is a reversal indicator.
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'in' backwards is 'ni'.
'ni'+'che'='NICHE'

Can you help me to learn more?

(Other definitions for niche that I've seen before include "Nook, cranny" , "comfortable situation" , "Suitable position (in market, life etc)" , "somewhere comfortable" , "Speciality" .)

I've seen this clue in The Daily Express.

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