Still fiery, entertained by revolutionary work in theatre (5)
I believe the answer is:
photo
'still' is the definition.
(I've seen this before)
'fiery entertained by revolutionary work in theatre' is the wordplay.
'fiery' becomes 'hot' (similar in meaning).
'entertained by' means one lot of letters goes inside another (inserted letters are hosted or entertained).
'revolutionary' shows that the letters should be reversed in order (letters revolve around).
'work in theatre' becomes 'op' (I can't explain this - if you can you should give a lot more credence to this answer).
'op' in reverse letter order is 'po'.
'hot' going within 'po' is 'PHOTO'.
Can you help me to learn more?
(Other definitions for photo that I've seen before include "Pic (abbr)" , "Picture, in short" , "Snap, pic" , "Camera image" , "Camera picture" .)