English underground worker’s back-to-front fur coat (6)
I believe the answer is:
ermine
'fur coat' is the definition.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for ermine that I've seen before include "White fur of weasel" , "White fur worn by some judges" , "special trimmings" , "Ceremonial fur" , "Winter fur of the stoat" .)