Run hard, finally coming to wood (4)
I believe the answer is:
dash
'run' is the definition.
(I know that dash is a type of run)
'hard finally coming to wood' is the wordplay.
'finally' indicates one should take the final letters.
'coming to' is a charade indicator (letters next to each other).
'wood' becomes 'ash' (wood from an ash tree).
The last letter of 'hard' is 'd'.
'd'+'ash'='DASH'
(Other definitions for dash that I've seen before include "instrument panel" , "Splash of colour" , "Morse feature" , "If you're smart, you'll cut one" , "Small amount -- move fast" .)