Clean off spear (5)
I believe the answer is:
lance
'spear' is the definition.
(I know that spear can be written as lance)
'clean off' is the wordplay.
'off' is an anagram indicator.
'clean' with letters rearranged gives 'LANCE'.
(Other definitions for lance that I've seen before include "Horseman's long weapon" , "A horse soldier's spear" , "Old cavalry weapon" , "Chap" , "Surgical knife" .)