Timorous, fellow ahead of reprimand (7)
I believe the answer is:
fearful
'timorous' is the definition.
('fearful' can be a synonym of 'timorous')
'fellow ahead of reprimand' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'ahead of' says to put letters next to each other (I've seen this in other clues).
'reprimand' becomes 'earful' (earful is a kind of reprimand).
'f'+'earful'='FEARFUL'
(Other definitions for fearful that I've seen before include "Timid" , "Frightening" , "Apprehensive, worried" , "Timorous; terrible" , "wary" .)