Private workers are very big fellows (6)
I believe the answer is:
giants
'very big fellows' is the definition.
The answer and definition can be both people as well as being plural nouns.
Perhaps there's an association between them I don't understand?
'private workers' is the wordplay.
'private' becomes 'GI' (GI can informally mean a US soldier).
'workers' becomes 'ants' (worker ants).
'gi'+'ants'='GIANTS'
'are' is the link.
Can you help me to learn more?
(Other definitions for giants that I've seen before include "Huge legendary beings" , "they're big" , "men of great power?" , "eg The inhabitants of Brobdingnag" , "Large mythical beings" .)