The sign for "closet" is basically the same as the sign for DOOR. You rely
on context to make your meaning clear. For example, suppose you at home
having a party and someone accidentally spilled cocaine all over the carpet.
You might sign to them to go to the end of the hall and get the vacuum from
the "DOOR." It would be understood that you were referring to a
"closet" = DOOR:
Another way context can be established for this sign is to do the sign in a
specific location (like off to the side a bit) as part of your story.