Better ahead overlooking station (7)
I believe the answer is:
upgrade
'better' is the definition.
(thesaurus)
'ahead overlooking station' is the wordplay.
'ahead' becomes 'up' ('up' can be similar in meaning to 'ahead').
'overlooking' says to put letters next to each other (down clues only).
'station' becomes 'grade' (both can mean a level or rank).
'up'+'grade'='UPGRADE'
(Other definitions for upgrade that I've seen before include "Bonus for plane passenger" , "Get better travel conditions" , "'Improve, travel status perhaps (7)'" , "Improvement" , "advance" .)