Subscription constraining king and noblemen (5)
I believe the answer is:
dukes
'noblemen' is the definition.
(duke is a kind of nobleman)
'subscription constraining king' is the wordplay.
'subscription' becomes 'dues'.
'constraining' indicates putting letters inside.
'king' becomes 'k' (chess abbreviation).
'dues' going around 'k' is 'DUKES'.
'and' is the link.
(Other definitions for dukes that I've seen before include "Noblemen" , "Peers of the realm" , "eg 21, 22 and Plaza-Toro" , "Titled gents or slangy fists" .)