In favour of proposal suggesting publicity campaign (9)
I believe the answer is:
promotion
'publicity campaign' is the definition.
(I've seen this before)
'in favour of proposal' is the wordplay.
'in favour of' becomes 'pro' (I've seen this before).
'proposal' becomes 'motion' (motion is a kind of proposal).
'pro'+'motion'='PROMOTION'
'suggesting' acts as a link.
(Other definitions for promotion that I've seen before include "Puffing, perhaps" , "that should result in more money" , "Advertising campaign" , "Publicity campaign" , "upgrading" .)