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.
Perhaps you can see an association between them that I can't see?
'try to hit the' is the wordplay.
'try to hit' becomes 'put' (I can't justify this - if you can 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" .)