Reason to ring? (4)

I believe the answer is:

call

I believe this clue is a double definition.

'reason' is the first definition.
(thesaurus)

'ring?' is the second definition.
('call' can be a synonym of 'ring')

'to' is the link.

(Other definitions for call that I've seen before include "Short visit" , "Ireland's ..., rugby anthem" , "Telephone - give a name" , "Visit; cry out" , "Shout - name" .)

I've seen this clue in the Evening Standard.

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