Runs and manages to find missing leader (5)
I believe the answer is:
races
'runs' is the definition.
('race' can be a synonym of 'run')
'manages to find missing leader' is the wordplay.
'manages to find' becomes 'traces' (to trace something is to find it).
'missing leader' means to remove the first letter (leader meaning lead letter).
'traces' with its initial letter taken away is 'RACES'.
'and' acts as a link.
(Other definitions for races that I've seen before include "Moves very fast" , "Speed competitions for various peoples" , "Sprint and marathon?" , "Events at Epsom or Ascot?" , "Rushes" .)