One can see when theyre open (7)
I believe the answer is:
eyelids
'theyre open' is the definition.
I can't judge whether this definition defines the answer.
'one can see' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
'see' could be 'eye' (I've seen this in another clue) and 'eye' is present in the answer.
The remaining letters 'lds' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'when' 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" .)