Pick an argument on the phone (7)
I believe the answer is:
appoint
'pick' is the definition.
(I've seen this before)
'an argument on the phone' is the wordplay.
I cannot really understand how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is located in the answer.
'on' is within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
The remaining letters 'app' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for appoint that I've seen before include "Delegate" , "Fix" , "Give job to" , "Designate (job)" , "Assign position to" .)