Shoots one below rib, retires, loses a life (7)
I believe the answer is:
birdies
'shoots' is the definition.
(birdiing is a kind of shooting)
'one below rib retires loses a life' is the wordplay.
'one below' means one lot of letters go next to another (in a down clue, some letters go below others).
'retires' is a reversal indicator.
'loses a life' becomes 'dies' (I can't justify this - if you can you should give a lot more credence to this answer).
'rib' back-to-front is 'bir'.
'bir' next to 'dies' is 'BIRDIES'.
Can you help me to learn more?
(Another definition for birdies that I've seen is " They're one under par".)