An unlicensed receiver (5)
I believe the answer is:
fence
'receiver' is the definition.
(I know that receiver can be written as fence)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for fence that I've seen before include "Obstacle to clear, in steeple-chasing" , "Receiver of stolen goods" , "With blade, fight" , "Enclosing barrier" , "crook" .)