Worry about daughter in revolutionary group (5)
I believe the answer is:
cadre
'revolutionary group' is the definition.
(cadre can mean a group of revolutionaries)
'worry about daughter in' is the wordplay.
'worry about' becomes 'care' (I've seen this in another clue).
'daughter' becomes 'd' (genealogical abbreviation).
'in' means one lot of letters goes inside another.
'care' going around 'd' is 'CADRE'.
(Other definitions for cadre that I've seen before include "Nucleus of key personnel" , "Political group" , "Group of key personnel" , "Nucleus, corps" , "Fighting unit" .)