In a raincoat, Joe's charming (5)
I believe the answer is:
magic
'charming' is the definition.
(I know that charming can be written as magic)
'in a raincoat joe's' is the wordplay.
'in' is an insertion indicator.
'a raincoat' becomes 'mac' (macintosh is a type of raincoat).
'joe' becomes 'GI' (GI Joe).
'mac' placed around 'gi' is 'MAGIC'.
(Other definitions for magic that I've seen before include "Necromancy" , "Brilliant -- deception" , "Entertainment at a children's party?" , "Art that supposedly invokes supernatural powers" , "Sprinkling of fairy dust" .)