Check popular group making case for power (7)
I believe the answer is:
inspect
'check' is the definition.
(I've seen this before)
'popular group making case for power' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'group' becomes 'sect' (I've seen this in other clues).
'making case for' means one lot of letters goes inside another (outside letters encase other letters).
'power' becomes 'p'.
'sect' going around 'p' is 'spect'.
'in'+'spect'='INSPECT'
(Other definitions for inspect that I've seen before include "Scrutinize, audit" , "Scan" , "Assess; examine" , "vet" , "Carefully examine" .)