First of Camorra dons turned clean (5)
I believe the answer is:
scour
'clean' is the definition.
(I've seen this before)
'first of camorra dons turned' is the wordplay.
'first of camorra' becomes 'c' (1st letter of 'camorra').
'dons' means one lot of letters goes inside another (don can mean to wear or be covered in).
'turned' becomes 'sour' (synonyms).
'c' placed inside 'sour' is 'SCOUR'.
(Other definitions for scour that I've seen before include "Turn upside down" , "purge" , "Hunt through" , "Clean by rubbing with an abrasive" , "Scrub clean" .)