Tout honest about representative ticket's source (7)
I believe the answer is:
trumpet
'tout' is the definition.
(thesaurus)
'honest about representative ticket's source' is the wordplay.
'honest' becomes 'true' (associated in meaning).
'about' is an insertion indicator.
'representative' becomes 'mp' (Member of Parliament).
'source' says to take the initial letters (source can mean a beginning or origin).
The initial letter of 'tickets' is 't'.
'true' enclosing 'mp' is 'trumpe'.
'trumpe'+'t'='TRUMPET'
(Other definitions for trumpet that I've seen before include "Play it" , "What elephants do" , "Metal wind instrument" , "Proclaim loudly" , "Brass musical instrument" .)