Thus allowed to make advances (7)
I believe the answer is:
solicit
'make advances' is the definition.
(thesaurus)
'thus allowed' is the wordplay.
'thus' becomes 'so' (synonyms).
'allowed' becomes 'licit' (I've seen this in other clues).
'so'+'licit'='SOLICIT'
'to' acts as a link.
(Other definitions for solicit that I've seen before include "Ask (favour)" , "Tout" , "Request urgently and/or persistently" , "Proposition" , "Invite, beg for" .)