That of the Barnet fair? (3)

I believe the answer is:

net

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

'that of the barnet fair?' is the definition.
I can't tell whether this defines the answer.

'of the barnet fair?' is the wordplay.
'of' says the answer is hidden in the clue.
'NET' can be found hidden inside 'barnet fair'.

Can you help me to learn more?

(Other definitions for net that I've seen before include "difficulty" , "Mesh; entrap" , "Mesh for the bottom line?" , "Catch; fine fabric" , "Open-mesh fabric" .)

I've seen this clue in the Evening Standard.

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