Advertising professional with formal proposal (9)
I believe the answer is:
promotion
'advertising' is the definition.
(thesaurus)
'professional with formal proposal' is the wordplay.
'professional' becomes 'pro' (abbreviation).
'with' is a charade indicator (letters next to each other).
'formal proposal' becomes 'motion' (I've seen this in another clue).
'pro'+'motion'='PROMOTION'
(Other definitions for promotion that I've seen before include "Advertising campaign" , "Step up" , "sales campaign" , "Puffing, perhaps" , "that should result in more money" .)