I'll marry most of entourage in turn (6)
I believe the answer is:
uniter
'i'll' is the definition.
I can't judge whether this defines the answer.
'marry most of entourage in turn' is the wordplay.
'marry' becomes 'unite' (I've seen this before).
'most of entourage in turn' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'unite'+'r'='UNITER'
Can you help me to learn more?
(Other definitions for uniter that I've seen before include "one getting married, perhaps" , "one joining" .)