Wangle a discount for the keeper (9)
I believe the answer is:
custodian
'the keeper' is the definition.
('custodian' can be a synonym of 'keeper')
'wangle a discount' is the wordplay.
'wangle' indicates an anagram (I've seen this in other clues).
'a'+'discount'='adiscount'
'adiscount' with letters rearranged gives 'CUSTODIAN'.
'for' acts as a link.
(Other definitions for custodian that I've seen before include "Guardian" , "Protector" , "museum keeper" , "Protector/guardian (of something)" , "One takes care of" .)