Tear apart material with speed (8)
I believe the answer is:
lacerate
'tear apart' is the definition.
(I've seen this in another clue)
'material with speed' is the wordplay.
'material' becomes 'lace' (lace is a kind of material).
'with' is a charade indicator (letters next to each other).
'speed' becomes 'rate' (both can mean pace).
'lace'+'rate'='LACERATE'
(Other definitions for lacerate that I've seen before include "Clear tea (anag.)" , "Tear or gash roughly" , "Cut, leaving jagged edges" , "Tear, rip (flesh or skin)" , "Cut or tear irregularly" .)