Impression made by one politician introducing bill (6)
I believe the answer is:
impact
'impression' is the definition.
(thesaurus)
'by one politician introducing bill' is the wordplay.
'by' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'politician' becomes 'mp'.
'introducing' means one lot of letters go next to another.
'bill' becomes 'act' (I've seen this in other clues**).
'i' put next to 'mp' is 'imp'.
'imp'+'act'='IMPACT'
'made' acts as a link.
(Other definitions for impact that I've seen before include "Force of colllision or blow" , "The force of one body against another" , "The force fo violent strike" , "Bear upon" , "Marked effect; hit" .)