Material on floor in prison I levered up (4)
I believe the answer is:
lino
'material on floor' is the definition.
'lino' can be an answer for 'material' (lino is a kind of material). I am unsure of the 'on floor' bit.
'in prison i levered up' is the wordplay.
'in' says the answer is hidden in the clue.
'up' is a reversal indicator (in down clue: letters go upwards).
'onil' is hidden within 'prison i levered'.
'onil' back-to-front is 'LINO'.
Can you help me to learn more?
(Other definitions for lino that I've seen before include "put this down?" , "Tough floor covering" , "'Floor covering, in short (4)'" , "Floor covering (abbr)" .)