Former Iranian leader cooking hash (4)
I believe the answer is:
shah
'former iranian leader' is the definition.
(I've seen this in another clue)
'cooking hash' is the wordplay.
'cooking' indicates an anagram (letters cooked up into a new form).
'hash' anagrammed gives 'SHAH'.
(Other definitions for shah that I've seen before include "Title of Iranian monarch" , "Former Iranian ruler" , "King of Persia" , "Deposed Iranian ruler" , "Persian monarch" .)