Had to go out East with the boss (4)
I believe the answer is:
head
'the boss' is the definition.
(I've seen this before)
'had to go out east' is the wordplay.
'had' becomes 'd' (I've seen this in other clues).
'to' says to put letters next to each other (I've seen this in other clues).
'go out east' becomes 'hea' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'd' after 'hea' is 'HEAD'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for head that I've seen before include "Chief; bonce" , "Skull" , "bean" , "Source of river, leader" , "Chief; go first" .)