Patrons unexpectedly elect to retain right of possession (9)
I believe the answer is:
clientele
'patrons' is the definition.
(I've seen this in another clue)
'unexpectedly elect to retain right of possession' is the wordplay.
'unexpectedly' indicates an anagram.
'to retain' means one lot of letters goes inside another.
'right of possession' becomes 'lien' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'elect' anagrammed gives 'ctele'.
'ctele' enclosing 'lien' is 'CLIENTELE'.
Can you help me to learn more?
(Other definitions for clientele that I've seen before include "A shop's customers" , "They patronise" , "Customers, collectively" , "Customers of a business" , "Patrons" .)