Lefty ordered to wash up (8)
I believe the answer is:
southpaw
'lefty' is the definition.
(synonyms)
'ordered to wash up' is the wordplay.
'ordered' indicates an anagram.
'to'+'wash'+'up'='towashup'
'towashup' with letters rearranged gives 'SOUTHPAW'.
(Other definitions for southpaw that I've seen before include "one leading from the right" , "To wash up (anag.)" , "One using left hand" , "Boxer who leads with the right hand" , "Left-handed pugilist" .)