Increase pace, winning (4,2)
I believe the answer is:
step up
'increase' is the definition.
('step-up' can be a synonym of 'increase')
'pace winning' is the wordplay.
'pace' becomes 'step' ('step' can be a synonym of 'pace'**).
'winning' becomes 'up' (I've seen this in other clues).
'step'+'up'='STEP-UP'
(Other definitions for step up that I've seen before include "- Bezukhov (War and Peace)" , "Accelerate - promotion" , "Increase as with pace - or ascend stair?" , "Approach" , "To be promoted" .)