Leaflet, one on grip (8)
I believe the answer is:
traction
'grip' is the definition.
('traction' can be a synonym of 'grip')
'leaflet one on' is the wordplay.
'leaflet' becomes 'tract' (I've seen this in other clues).
'one' becomes 'i' (Roman numeral).
'tract'+'i'+'on'='TRACTION'
(Other definitions for traction that I've seen before include "Act of pulling" , "The action of drawing or pulling over a road or track" , "Use of weights and pulleys to heal a fracture" , "Continuous pull on limb in medical treatment" , "Action of drawing or pulling something" .)