Love playing one right into the middle of the green (5)
I believe the answer is:
olive
'green' is the definition.
(olive green is a kind of green)
'love playing one right into the middle' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'playing one right' becomes 'liv' (I can't explain this - if you can you should give a lot more credence to this answer).
'into' becomes 'a one for' (I've seen this before).
'the middle' means to look at the middle letters.
The middle letter of 'aonefor' is 'e'.
'o'+'liv'+'e'='OLIVE'
'of the' acts as a link.
Can you help me to learn more?
(Other definitions for olive that I've seen before include "Girl's name; tree" , "It's branch is a symbol of peace" , "girl" , "This branch is offered to show peace" , "Fruit also used to make oil" .)