A little parcel at Christmas fitting through the door (5)
I believe the answer is:
latch
'the door' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'a little parcel at christmas fitting' is the wordplay.
'a little' indicates the answer is hidden within the clue (a little bit of the clue).
'LATCH' is hidden within 'parcel at christmas fitting'.
'through' is the link.
Can you help me to learn more?
(Other definitions for latch that I've seen before include "Bar to close" , "Device for opening door" , "Device to hold door shut" , "Gate fastener" , "Small bar for fastening a door" .)