Weakly proclaimed, but at regular intervals (6)

I believe the answer is:

weekly

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'at regular intervals' is the definition.
I can't judge whether this defines the answer.

'weakly proclaimed but' is the wordplay.
'weakly' becomes 'weak' (synonyms).
'proclaimed' indicates a 'sounds like' (homophone) clue.
'but' becomes 'ly' (I can't justify this - if you can you should believe this answer much more).
'weak' is a homophone of 'week'.
'week'+'ly'='WEEKLY'

Can you help me to learn more?

(Other definitions for weekly that I've seen before include "magazine" , "eg Every Tuesday" , "Occurring every seven days" , "52 times a year" , "Hebdomadal" .)

I've seen this clue in the Evening Standard.

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