Ruffled the in-crowd? (5)
I believe the answer is:
upset
'ruffled' is the definition.
(I've seen this in another clue)
'the in-crowd?' is the wordplay.
'the in' becomes 'up' (I can't explain this - if you can you should give a lot more credence to this answer).
'crowd?' becomes 'set' (I've seen this in other clues).
'up'+'set'='UPSET'
Can you help me to learn more?
(Other definitions for upset that I've seen before include "Make unhappy; knock over" , "Shock result!" , "Unexpected defeat - tipped over" , "Sad" , "'Disturbed, agitated (5)'" .)