One star-crossed lawmaker (7)
I believe the answer is:
senator
'lawmaker' is the definition.
(senator is a kind of lawmaker)
'one star-crossed' is the wordplay.
'crossed' indicates an anagram.
'one'+'star'='onestar'
'onestar' anagrammed gives 'SENATOR'.
(Other definitions for senator that I've seen before include "US/Roman politician" , "Member of a governing body" , "Roman legislator" , "Politician involved in treason" , "One of 100 on Capitol Hill" .)