Down south and missing north (3)
I believe the answer is:
sad
'down' is the definition.
(I've seen this in another clue)
'south and missing north' is the wordplay.
'south' becomes 's' (abbreviation).
'missing' is a deletion indicator.
'north' becomes 'N' (abbreviation).
'and' with 'n' taken away is 'ad'.
's'+'ad'='SAD'
(Other definitions for sad that I've seen before include "Tragic" , "Mournful and depressed" , "Blue" , "Melancholy, depressed" , "Melancholy, downhearted" .)