Scared fellow caught in a sudden attack (6)
I believe the answer is:
afraid
'scared' is the definition.
('afraid' can be similar in meaning to 'scared')
'fellow caught in a sudden attack' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'caught in' is an insertion indicator.
'sudden attack' becomes 'raid' (I've seen this before).
'a'+'raid'='araid'
'f' inserted into 'araid' is 'AFRAID'.
(Other definitions for afraid that I've seen before include "Scared - politely regretful" , "Regretfully" , "wind up" , "feeling scared" , "cowardly" .)