Was Alexander the gang headman? (6,2,3,4)

'was alexander' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'gang headman?' is the wordplay.
I cannot really understand how this works, but
'gang' could be 'band' (both can mean a group of people) and 'band' is found in the answer.
'headman?' could be 'leader' (headman is a kind of leader) and 'leader' is found within the answer.
The remaining letters 'ofthe' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

'the' is the link.

Can you help me to learn more?