Spot a worker in the dark (4)
I believe the answer is:
mole
'spot' is the definition.
(spot or blemish on the skin)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for mole that I've seen before include "Spy - creator of hills?" , "Burrowing mammal with velvety fur" , "Spot - burrowing mammal" , "Tunneller" , "Small burrowing animal" .)