Bandage bits up (5)
I believe the answer is:
strap
'bandage' is the definition.
(thesaurus)
'bits up' is the wordplay.
'bits' becomes 'parts' (I've seen this before).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'parts' written backwards gives 'STRAP'.
(Other definitions for strap that I've seen before include "Belt; leather strip" , "Leather thong" , "loopy band" , "Elongated leather strip" , "Strong band for binding luggage etc" .)