Leg gets stuck in bit of wood, running (6)
I believe the answer is:
loping
'running' is the definition.
(loping is a kind of running)
'leg gets stuck in bit of wood' is the wordplay.
'leg' becomes 'pin' (pin is a kind of leg).
'gets stuck in' indicates putting letters inside.
'bit of wood' becomes 'log'.
'pin' placed within 'log' is 'LOPING'.
(Other definitions for loping that I've seen before include "Walking with long strides" , "Running with long strides" .)