All the lawyers in the county booked (6)

'the county booked' is the definition.
(fictional county in books by Anthony Trollope)

'all the lawyers' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'lawyers' could be 'bar' (the bar can mean the legal profession) and 'bar' is found within the answer.
The remaining letters 'se' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'in' acts as a link.

Can you help me to learn more?