Adee sad about the lowest lake in the world (4,3)
I believe the answer is:
dead sea
'lowest lake in the world' is the definition.
(I've seen this before)
'adee sad about' is the wordplay.
'about' indicates an anagram.
'adee'+'sad'='adeesad'
'adeesad' anagrammed gives 'DEAD SEA'.
'the' acts as a link.
(Other definitions for dead sea that I've seen before include "Lake in Jordan valley where Scrolls were found" , "The lake that's a late ocean" , "Saltwater lake in the Jordan valley" , "Middle East saltwater lake, almost 1,300 feet below sea level" , "Inland salt lake in the Jordan valley of Israel" .)