False material for jumpers (5)
I believe the answer is:
fleas
'for jumpers' is the definition.
(I've seen this before)
'false material' is the wordplay.
'material' indicates an anagram (the letters provide the material for a new word).
'false' with letters rearranged gives 'FLEAS'.
(Other definitions for fleas that I've seen before include "jumpers" , "Leaping parasites" , "Insects" .)