Like a tight garment for Spooner, being deceptive (10)

I believe the answer is:

humbugging

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

'being deceptive' is the definition.
(humbug can mean to trick or deceive)

I don't understand how the remainder of the clue works.

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.

Connecting...