It’s just an illusion that Joe’s in a raincoat (5)

I believe the answer is:

magic

I'm a little stuck... Click here to teach me more about this clue!

'it's just an illusion' is the definition.
I can't judge whether this defines the answer.

'joe's in a raincoat' is the wordplay.
'joe' becomes 'gi' (GI Joe).
'in' indicates putting letters inside.
'a raincoat' becomes 'mac' (mac is a kind of raincoat).
'gi' going inside 'mac' is 'MAGIC'.

'that' is the link.

Can you help me to learn more?

(Other definitions for magic that I've seen before include "Conjuror's art" , "Unexpectedly produce" , "Wonderful" , "Wizardry - wizard!" , "Sprinkling of fairy dust" .)

I've seen this clue in the Evening Standard.

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