Substitute campanologist? (6)

I believe the answer is:

ringer

I believe this is a double definition.

'substitute' is the first definition.
(thesaurus)

'campanologist?' is the second definition.
(I've seen this before)

(Other definitions for ringer that I've seen before include "Doppelganger" , "One making the toll" , "Campanologist - spitting image" , "clanger?" , "bell" .)

I've seen this clue in the Evening Standard.

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