Golf shot starts to spin hard after nasty knock (5)
I believe the answer is:
shank
'golf shot' is the definition.
(I know that shank is a type of golf shot)
'starts to spin hard after nasty knock' is the wordplay.
'starts to' says to take the initial letters.
The first letters of 'spin hard after nasty knock' is 'SHANK'.
(Other definitions for shank that I've seen before include "If red, flyer" , "Cut of meat; leg" , "Cut of meat from lower part of foreleg" , "The shin" .)