Slimy thing, sock (4)
I believe the answer is:
slug
This could be a double definition.
'slimy thing' is the first definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'sock' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for slug that I've seen before include "Bullet; swig" , "Shell-less mollusc ? bullet" , "Live" , "Projectile fired from a gun" , "Slimy fellow in bed" .)