Wash unusually large item of clothing (5)
I believe the answer is:
shawl
'item of clothing' is the definition.
(type of garment)
'wash unusually large' is the wordplay.
'unusually' indicates an anagram.
'large' becomes 'l'.
'wash' anagrammed gives 'shaw'.
'shaw'+'l'='SHAWL'
(Other definitions for shawl that I've seen before include "Wrap or scarf" , "Wrapped clothes item" , "Fabric wrap" , "Female garment" , "Cape" .)