Round part of a doorbell (3)

I believe the answer is:

orb

'round' is the definition.
(thesaurus)

'part of a doorbell' is the wordplay.
'part of' says the answer is hidden in the clue.
'ORB' is hidden within 'doorbell'.

(Other definitions for orb that I've seen before include "Ornamental globe" , "The World" , "Jewelled ornament" , "Ceremonial globe carried by a monarch" , "Poetically eye" .)

I've seen this clue in the Evening Standard.

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