Moderate old Conservatives, after revolution, in nervy state (4)
I believe the answer is:
stew
'nervy state' is the definition.
(being in a stew means being nervous)
'moderate old conservatives after revolution' is the wordplay.
'moderate old conservatives' becomes 'wets' (1980s term for moderate Conservatives).
'after revolution' says the letters should be written in reverse (letters revolve back).
'wets' back-to-front is 'STEW'.
'in' acts as a link.
(Other definitions for stew that I've seen before include "Get anxious" , "Fret" , "Boil slowly" , "Agitated state" , "Artificial oyster bed" .)