Bit of surplus luggage that can be a nuisance (4)
I believe the answer is:
slug
'bit of surplus luggage that can be a nuisance' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'bit of surplus luggage that' is the wordplay.
'bit of' indicates the answer is hidden within the clue.
'SLUG' is hidden in the letters of 'surplus luggage that'.
Can you help me to learn more?
(Other definitions for slug that I've seen before include "Some whisky perhaps" , "Pellet; deal thumping blows" , "Slimy gastropod" , "slimy type" , "Shell-less mollusc ? bullet" .)