Since final traffic concludes, climbs (7)
I believe the answer is:
ascends
'climbs' is the definition.
(I've seen this in another clue)
'since final traffic concludes' is the wordplay.
'since' becomes 'as' (I've seen this in other clues).
'final' suggests the final letters.
'concludes' becomes 'ends' (I've seen this in another clue).
The final letter of 'traffic' is 'c'.
'as'+'c'+'ends'='ASCENDS'
(Other definitions for ascends that I've seen before include "Climbs, mounts" , "Rises" , "Travels upwards" , "Moves upwards" .)