They're protected by lids (4)
I believe the answer is:
eyes
'they're protected by lids' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eyes that I've seen before include "The first things children open on Christmas Day" , "Narrowly watches" , "Peepers" , "Marks on potatoes" , "Regards -- features of a potato" .)