Leader is corrupt it's understood (8)
I believe the answer is:
realised
'understood' is the definition.
(I've seen this before)
'leader is corrupt' is the wordplay.
'corrupt' indicates an anagram.
'leader'+'is'='leaderis'
'leaderis' is an anagram of 'REALISED'.
'it's' is the link.
(Other definitions for realised that I've seen before include "Became aware of in sidereal way" , "Came to be aware" , "Fully comprehended" , "Understood - cashed in" , "Sidereal (anag)" .)