Fellow's hot in trimmed cloak (4)
I believe the answer is:
chap
'fellow's' is the definition.
(both can mean a man)
'hot in trimmed cloak' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'in trimmed' becomes 'cap' (I can't explain this - if you can you should believe this answer much more).
'cloak' indicates putting letters inside.
'h' going inside 'cap' is 'CHAP'.
Can you help me to learn more?
(Other definitions for chap that I've seen before include "Fellow < makes > crack" , "Split in skin" , "Man, sore patch" , "Become sore; fellow" , "(Of skin) become sore" .)