Disorder of some leeches (5)
I believe the answer is:
melee
'disorder' is the definition.
(thesaurus)
'of some leeches' is the wordplay.
'of' indicates the answer is hidden within the clue.
'MELEE' is hidden within 'some leeches'.
(Other definitions for melee that I've seen before include "Affray; muddled group" , "Scrap" , "Scrimmage" , "confused group" , "Confused fight or scuffle" .)