Class warfare, I think, somewhat regressive (4)
I believe the answer is:
tier
'class' is the definition.
(I've seen this in another clue)
'warfare i think somewhat regressive' is the wordplay.
'somewhat' indicates a hidden word.
'regressive' says the letters should be written in reverse (to regress is to go backwards).
'reit' is hidden within 'warfare i think'.
'reit' back-to-front is 'TIER'.
(Other definitions for tier that I've seen before include "he hasn't won?" , "Hierarchical level" , "I might draw" , "band" , "Wedding cake feature" .)