One's boring coat (6)

I believe the answer is:
anorak
This clue might be a double definition.
'one's boring' is the first definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'coat' is the second definition.
(type of coat)
Can you help me to learn more?
(Other definitions for anorak that I've seen before include "Jacket for an obsessive?" , "Jacket for obsessives?" , "Garment (worn by boring obsessive?)" , "Trivia obsessive" , "Boringly obsessive person" .)
