Those waiting to fight in the army? Mostly workers! (8)
I believe the answer is:
servants
'those waiting' is the definition.
(I've seen this before)
'fight in the army? mostly workers' is the wordplay.
I cannot quite understand how this works, but
'workers' could be 'ants' (I've seen this before) and 'ants' is located in the answer.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for servants that I've seen before include "Household staff" , "They look after the personal needs of others" , "They're employed in the service of government" , "those waiting" , "Domestic staff" .)