Durable woollen material worn by worker can be found at army base (8)
I believe the answer is:
sergeant
'durable woollen' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'material worn by worker can be found at army base' is the wordplay.
I cannot really see how this works, but
'material' could be 'serge' (serge is a kind of material) and 'serge' is found within the answer.
'worker' could be 'ant' (worker is a type of ant) and 'ant' is found within the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for sergeant that I've seen before include "Pepper, say" , "Troy" , "Military or police officer" , "Army rank" , "military man" .)