Turning, knocks into pole (4)
I believe the answer is:
spar
'pole' is the definition.
(spar is a kind of pole)
'turning knocks' is the wordplay.
'turning' is a reversal indicator.
'knocks' becomes 'raps' ('rap' can be a synonym of 'knock').
'raps' reversed gives 'SPAR'.
'into' is the link.
(Other definitions for spar that I've seen before include "Fight - something probably rigged?" , "Pole-shaped part of the rigging" , "Fight (in training) - pole (on boat)" , "Mineral; plane's wing beam" , "supporting member" .)