One making a call to arrange replay? (7)
I believe the answer is:
decider
'one' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's an association between them I don't understand?
'a call to arrange replay?' is the wordplay.
'a call' becomes 'decide' (I've seen this in another clue).
'to arrange replay?' becomes 'r' (I can't explain this - if you can you should give a lot more credence to this answer).
'decide'+'r'='DECIDER'
'making' is the link.
Can you help me to learn more?
(Other definitions for decider that I've seen before include "It settles the matter" , "It produces a winner after a drawn series" , "vital match" , "Settler" , "Extra period of play to settle a draw" .)