Corrupt idea: deal that makes capital (8)
I believe the answer is:
adelaide
'capital' is the definition.
(Adelaide is an example)
'corrupt idea deal' is the wordplay.
'corrupt' indicates anagramming the letters.
'idea'+'deal'='ideadeal'
'ideadeal' is an anagram of 'ADELAIDE'.
'that makes' acts as a link.
(Other definitions for adelaide that I've seen before include "State capital of South Australia" , "Antipodean city" , "Australian capital" , "Australian location" , "close to Detroit" .)