Criminal steals decorative item (6)
I believe the answer is:
tassel
'decorative item' is the definition.
'criminal steals' is the wordplay.
'criminal' is an anagram indicator.
'steals' is an anagram of 'TASSEL'.
(Other definitions for tassel that I've seen before include "Decorative tuft of threads" , "Decorative hanging tuft" , "Bunch of cords as adornment" , "Decorative bunch of cords" , "Part of a flower" .)