Crossword Genius

Watch cruise ship that's used to bring out pupils?

Ross

I believe the answer is:

eyeliner

I'm a little stuck... Click here to teach me more about this clue!

'used to bring out pupils?' is the definition.
I can't tell whether this definition defines the answer.

'watch cruise ship' is the wordplay.
'watch' becomes 'eye' (I've seen this before).
'cruise ship' becomes 'liner' (I've seen this before).
'eye'+'liner'='EYELINER'

'that's' acts as a link.

Can you help me to learn more?

(Other definitions for eyeliner that I've seen before include "Item of 25dn" , "Makeup for the peepers" , "Facial cosmetic" , "kind of cosmetic" , "highlight for look-out" .)

I've seen this clue in The Daily Mail.
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