See meltwater then? (6)
I believe the answer is:
notice
This could be a double definition.
'see' is the first definition.
(notice can mean to see or realise)
'meltwater then?' is the second definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
(Other definitions for notice that I've seen before include "Observe, become aware of" , "This is usually given before quitting job" , "Statement that one is to leave job on given date" , "Advance indication of intention to resign" , "Notification" .)