Start working round hems in those torn rags (7)
I believe the answer is:
tatters
'torn rags' is the definition.
'start working round hems in those' is the wordplay.
'working' is an anagram indicator.
'round' indicates putting letters inside.
'hems in' says to hollow out the word (remove centre letters) (the outside letters or hems of).
'those' with its centre removed is 'te'.
'start' is an anagram of 'tatrs'.
'tatrs' going around 'te' is 'TATTERS'.
(Other definitions for tatters that I've seen before include "Rags, shreds" , "Torn pieces of cloth" , "Rags and torn pieces" .)