Clean up badly again (4)
I believe the answer is:
pure
'clean' is the definition.
('pure' can be similar in meaning to 'clean')
'up badly again' is the wordplay.
'badly' is an anagram indicator.
'again' becomes 're'.
'up' is an anagram of 'pu'.
'pu'+'re'='PURE'
(Other definitions for pure that I've seen before include "Innocent; unsullied" , "Not mixed with anything else" , "Not mixed or adulterated" , "Unadulterated" , "Untainted" .)