Tear fabric with speed (8)
I believe the answer is:
lacerate
'tear' is the definition.
(lacerating is a kind of tearing)
'fabric with speed' is the wordplay.
'fabric' becomes 'lace' (lace is a kind of fabric).
'with' says to put 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 "Harrow" , "Slash" , "Injure be tearing, wound roughly" , "Tear, wound, hurt" , "Tear roughly, cut jaggedly" .)