Strand of yarn spoiled red hat (6)
I believe the answer is:
thread
'strand of yarn' is the definition.
(I've seen this before)
'spoiled red hat' is the wordplay.
'spoiled' indicates anagramming the letters.
'red'+'hat'='redhat'
'redhat' with letters rearranged gives 'THREAD'.
(Other definitions for thread that I've seen before include "Ridge around a screw" , "Strand of cotton or other fibre" , "Filament; connecting link" , "Strand for sewing" , "'Strand of cotton, silk etc (6)'" .)