It contains something filling for the smoker (5)
I believe the answer is:
pouch
This might be a double definition.
'it contains something filling' is the first definition.
The definition suggests a singular noun which matches the answer.
'smoker' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'for the' is the link.
Can you help me to learn more?
(Other definitions for pouch that I've seen before include "Container for tobacco or young" , "Bag" , "Marsupial's baby carrier" , "Kangaroo's pocket" , "joey's home" .)