Fasten on wooden pin (3,3)
I believe the answer is:
peg leg
'wooden pin' is the definition.
(pin can mean a leg)
'fasten on' is the wordplay.
'fasten' becomes 'peg' (to fasten with a peg).
'on' becomes 'leg' (cricket term, fielding positions).
'peg'+'leg'='PEG-LEG'
(Other definitions for peg leg that I've seen before include "Artificial limb (usually of wood)" , "Long John Silver, for instance" , "Informally, an artificial lower limb" , "(Person with) artificial limb" , "Artificial limb (informal)" .)