Escorts for one American boy, eating main up or starter (6,5)

'escorts for one' is the definition.
(I know that date is a type of buddy)

'american boy eating main up or starter' is the wordplay.
I cannot quite see how this works, but
'american' could be 'usa' and 'usa' is located in the answer.
'boy' could be 'cal' and 'cal' is present in the remaining letters.
The remaining letters 'agent' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

Can you help me to learn more?