Bill calling for support (10)

I believe the answer is:

advocation

'support' is the definition.

'bill calling' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'calling' becomes 'vocation' (synonyms).
'ad'+'vocation'='ADVOCATION'

'for' is the link.

(Another definition for advocation that I've seen is " The recommending".)

I've seen this clue in The Guardian.

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