They provide cover for the pupils (7)
I believe the answer is:
eyelids
'the pupils' is the definition.
The answer and definition can be both body parts as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
'they provide cover' is the wordplay.
I cannot quite see how this works, but
'cover' could be 'lid' (lid is a kind of cover) and 'lid' is found in the answer.
The remaining letters 'eyes' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'for' acts as a link.
Can you help me to learn more?
(Other definitions for eyelids that I've seen before include "covers for lamps" , "covers for lights?" , "They drop in sleep" .)