Dishonest Tory leader protected by fishy organisation (6)
I believe the answer is:
shifty
'dishonest' is the definition.
(thesaurus)
'tory leader protected by fishy organisation' is the wordplay.
'leader' says to take the initial letters.
'protected by' is an insertion indicator (inserted letters are held or protected).
'organisation' indicates anagramming the letters.
The initial letter of 'tory' is 't'.
'fishy' is an anagram of 'shify'.
't' inserted inside 'shify' is 'SHIFTY'.
(Other definitions for shifty that I've seen before include "Sly, shady" , "Appearing evasive" , "Suspicious-looking" , "Constantly changing; deceitful, evasive" , "Furtive" .)