Above which to be high and dry (3,5)
I believe the answer is:
sea level
'dry' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for sea level that I've seen before include "Standard for measuring map heights" , "Altitude reference point" , "Zero point for map heights" , "0 feet?" , "Reference point for heights" .)