Joint goes to the bishop's head! (5)
I believe the answer is:
mitre
'joint' is the definition.
(I know that mitre is a type of joint)
'the bishop's head' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'mire' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'goes to' acts as a link.
Can you help me to learn more?
(Other definitions for mitre that I've seen before include "Type of joint - bishop's hat" , "Bishop's tall headdress" , "Item of headgear" , "One identifies bishop" , "See boss gear up" .)