Crossword Genius

Ringing up here is not toll-free (6)

Ross

I believe the answer is:

belfry

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

'ringing up here' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.

'is not toll-free' is the wordplay.
I cannot quite understand how this works, but
'is' could be 'be' and 'be' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for belfry that I've seen before include "Part of a tower or steeple" , "Bats in the ...... is slangily crazy" , "Where to find peal" , "Part of a church tower" , "Place for church bells" .)

I've seen this clue in The Independent.
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