For dashing fellow, entering service is hard (7)
I believe the answer is:
raffish
'for dashing' is the definition.
('raffish' can be a synonym of 'dashing')
'fellow entering service is hard' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'entering' is an insertion indicator.
'service' becomes 'raf' (**).
'hard' becomes 'h'.
'f' going within 'raf' is 'raff'.
'raff'+'is'+'h'='RAFFISH'
(Other definitions for raffish that I've seen before include "Disreputable but attractive" , "Tawdry" , "Dashing" , "flashy and careless" , "bohemian" .)