Slash fabric having awful tear (8)
I believe the answer is:
lacerate
'slash' is the definition.
(I've seen this before)
'fabric having awful tear' is the wordplay.
'fabric' becomes 'lace' (lace is a kind of fabric).
'having' means one lot of letters goes inside another.
'awful' indicates anagramming the letters.
'tear' is an anagram of 'erat'.
'lace' enclosing 'erat' is 'LACERATE'.
(Other definitions for lacerate that I've seen before include "Cut or tear irregularly" , "Tear or cut (flesh) deeply" , "Clare ate (anag)" , "Clear tea (anag.)" , "Tear, wound, hurt" .)