Balls from iron in golf, hit stroke over middle of green (9)
I believe the answer is:
grapeshot
'balls from iron' is the definition.
(ammunition consisting of metal balls)
'golf hit stroke over middle of green' is the wordplay.
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'hit' becomes 'rap' (I've seen this in other clues**).
'stroke' becomes 'shot' (shot is a kind of stroke).
'over' is an insertion indicator.
'middle of' says to take the centre.
The middle of 'green' is 'e'.
'rap'+'shot'='rapshot'
'rapshot' placed around 'e' is 'rapeshot'.
'g'+'rapeshot'='GRAPESHOT'
'in' acts as a link.
(Other definitions for grapeshot that I've seen before include "slugs?" , "Charge for barrel" , "one could get peppered with it!" , "Small iron balls fired from a cannon" , "Great Balls of Fire" .)