Hole in one? A true shot (8)
I believe the answer is:
aperture
'hole' is the definition.
(aperture is a kind of hole)
'one? a true shot' is the wordplay.
'one?' becomes 'a'.
'a' becomes 'per'.
'shot' indicates an anagram.
'true' is an anagram of 'ture'.
'a'+'per'+'ture'='APERTURE'
'in' acts as a link.
(Other definitions for aperture that I've seen before include "Small hole or opening" , "Device controlling amount of light admitted" , "Crack" , "Narrow opening" , "Opening through which light enters a camera" .)