Cut up skittles (4)
I believe the answer is:
snip
'cut' is the definition.
(snip means to cut)
'up skittles' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'skittles' becomes 'pins' (as in ten-pin bowling).
'pins' back-to-front is 'SNIP'.
(Other definitions for snip that I've seen before include "Cut - prune" , "Cut - certainty" , "Bargain (coll)" , "Cut off a small bit" , "Bargain (informal)" .)