Scotsman in rainwear (3)
I believe the answer is:
mac
This could be a double definition.
'scotsman' is the first definition.
'rainwear' is the second definition.
Both the answer and definition are singular nouns.
Perhaps you can see an association between them that I can't see?
'in' is the link.
Can you help me to learn more?
(Other definitions for mac that I've seen before include "laptop?" , "Coat - computer" , "A rainproof" , "PC" , "A Gaelic son, often in name" .)