Try to hit the ball out of sight! (4)
I believe the answer is:
putt
'ball out of sight' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'try to hit the' is the wordplay.
'try to hit' becomes 'put' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'put'+'t'='PUTT'
Can you help me to learn more?
(Other definitions for putt that I've seen before include "that's not needed if you chip in" , "Green stroke" , "Strike golf ball on green" , "Play ball on green" , "Golf stroke near hole" .)