A lot of doctors left Georgia, teaming up and coming together as one (12)

'teaming up and coming together as one' is the definition.
I can't judge whether this definition defines the answer.

'a lot of doctors left georgia' is the wordplay.
I cannot quite see how this works, but
'a' is found in the answer.
'lot' could be 'm' and 'm' is found within the answer.
'left' could be 'al' (I've seen this in other clues) and 'al' is found within the answer.
'georgia' could be 'ga' (abbreviation for the US state) and 'ga' is present in the answer.
The remaining letters 'mating' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?