Politician submitted good bill last month, one fit for Congress (10,5)
I believe the answer is:
consenting adult
'one fit for congress' is the definition.
(congress can mean sex)
'politician submitted good bill last month' is the wordplay.
'politician' becomes 'con'.
'submitted' becomes 'sentin' (I've seen this before).
'good' becomes 'g' (abbreviation).
'bill' becomes 'ad' (advertisement stuck on wall).
'last month' becomes 'ult' (I've seen this before).
'con'+'sentin'+'g'+'ad'+'ult'='CONSENTING ADULT'
(Another definition for consenting adult that I've seen is " Mature type willing to have sex".)