Wherewithal to exploit core users (9)
I believe the answer is:
resources
'wherewithal' is the definition.
(thesaurus)
'exploit core users' is the wordplay.
'exploit' indicates anagramming the letters (I've seen 'exploited' mean this).
'core'+'users'='coreusers'
'coreusers' is an anagram of 'RESOURCES'.
'to' is the link.
(Other definitions for resources that I've seen before include "country's means of defence" , "Personal attributes" , "Useful materials, assets" , "funds" , "capital!" .)