Person running on track's the one I report to (4,7)
I believe the answer is:
line manager
'the one i report to' is the definition.
(employees report to a line manager)
'person running on track's' is the wordplay.
'person running' becomes 'manager' (somebody who runs things).
'on' says to put letters next to each other.
'track' becomes 'line' (line is a kind of track).
'manager' put after 'line' is 'LINE MANAGER'.
(Other definitions for line manager that I've seen before include "Immediate boss" , "fond of angling?" , "Person directly responsible for an employee" .)