Tom’s not in love with this garment (4)
I believe the answer is:
coat
'love with this garment' is the definition.
'coat' can be an answer for 'garment' (coat is a kind of garment). I am not sure about the rest of the definition.
'tom's not in' is the wordplay.
'tom' becomes 'cat' (I have seen 'A tom ' mean 'cat' so perhaps 'tom' could also mean 'cat').
'not' becomes 'o' (I've seen this in other clues).
'in' is an insertion indicator.
'cat' placed around 'o' is 'COAT'.
Can you help me to learn more?
(Other definitions for coat that I've seen before include "Warm outerwear" , "Overgarment" , "Fleece" , "Outer garment" , "Outer covering" .)