One's out – to score? (7)
I believe the answer is:
striker
'one's out to score?' is the definition.
I can't tell whether this definition defines the answer.
'one's out to score?' is the wordplay.
'one's out' becomes 'r' (I can't explain this - if you can you should give a lot more credence to this answer).
'to' says to put letters next to each other (I've seen this in other clues).
'score?' becomes 'strike' (strike is a kind of score).
'r' put after 'strike' is 'STRIKER'.
Can you help me to learn more?
(Other definitions for striker that I've seen before include "Someone facing" , "A forward on a soccer team" , "one who's out?" , "Football attacker" , "Perhaps a match" .)