Bump on a lid (4)
I believe the answer is:
stye
'bump on a lid' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stye that I've seen before include "Animal pen" , "Eyelid sore" , "Inflamed swelling on the edge of an eyelid" , "dump" , "Climb" .)