There may be a catch in it (4)

I believe the answer is:

trap

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

'it' is the definition.
The definition suggests a singular noun which matches the answer.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for trap that I've seen before include "Control ball" , "Ambush" , "website?" , "Vehicle" , "that may catch a speeding motorist" .)

I've seen this clue in the Evening Standard and The Globe and Mail.

Want a hint initially instead of a full solution? Install my app