Such pencils don't write (7)
I believe the answer is:
styptic
'such' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for styptic that I've seen before include "Stopping bleeding" , "This pencil checks bleeding as from shaving" , "Checking blood flow like shaving pencil" .)