Herds disturbed by scrap (5)
I believe the answer is:
shred
'scrap' is the definition.
(both can mean a small amount of material)
'herds disturbed' is the wordplay.
'disturbed' indicates anagramming the letters (the order of letters is disturbed).
'herds' is an anagram of 'SHRED'.
'by' acts as a link.
(Other definitions for shred that I've seen before include "Torn strip of cloth" , "Tear into scraps" , "Bit of rag" , "Dispose of" , "Tatter; small amount" .)