Fellow might, following workforce (8)
I believe the answer is:
manpower
'workforce' is the definition.
(I've seen this before)
'fellow might following' is the wordplay.
'fellow' becomes 'man' (fellow can mean a man).
'might' becomes 'power' (being mighty).
'following' means one lot of letters go next to another.
'man'+'power'='MANPOWER'
(Other definitions for manpower that I've seen before include "Work force" , "People available for work" , "Work effort" , "Workforce" , "Staff resources" .)