Solicit (6)
'solicit' is the definition.
(synonyms)
This is all the clue.
(Other definitions for accost that I've seen before include "Approach boldly, solicit" , "Come boldly up to" , "Approach or confront boldly" , "Meet and greet" , "Waylay" .)
'solicit' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for petition that I've seen before include "Request (often by many)" , "Entreaty" , "Formal request with many signatures" , "Written request" , "Formal request submitted to authority" .)