The fabric I harm, tearing a hole in it (6)
I believe the answer is:
mohair
'the fabric' is the definition.
(mohair is a kind of fabric)
'i harm tearing a hole in it' is the wordplay.
'tearing' indicates anagramming the letters.
'a hole' becomes 'o'.
'in it' means one lot of letters goes inside another.
'i'+'harm'='iharm'
'iharm' with letters rearranged gives 'mhair'.
'mhair' going around 'o' is 'MOHAIR'.
(Other definitions for mohair that I've seen before include "It comes from the Angora goat" , "Angora goat yarn" , "Fine hair fabric" , "Yarn provided by goats" , "Fabric made from the coat of an Angora goat" .)