Expected to be outside the King's Head with a nobleman (3)
I believe the answer is:
'expected' is the definition.
(similar in meaning)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for due that I've seen before include "Appropriate - fee - requiring payment" , "Appropriate - fee - now owing" , "Expected; appropriate" , "Ripe for payment or arrival" , "Scheduled to arrive" .)