Petition therefore within the law (7)
I believe the answer is:
solicit
'petition' is the definition.
(thesaurus)
'therefore within the law' is the wordplay.
'therefore' becomes 'so'.
'within the law' becomes 'licit' (I've seen this before).
'so'+'licit'='SOLICIT'
(Other definitions for solicit that I've seen before include "Ask earnestly,seek to obtain" , "Beg or court" , "Beg - hustle" , "Ask earnestly about colitis" , "Request, canvas" .)