After a short time, moved up and down (6)
I believe the answer is:
'down' is the definition.
(both can mean sad)
'after a short time moved up' is the wordplay.
'after' means one lot of letters go next to another.
'a short time' becomes 'mo' (slang abbreviation for 'moment').
'moved up' becomes 'rose' (eg rose up into the air).
'mo' put next to 'rose' is 'MOROSE'.
'and' is the link.
(Other definitions for morose that I've seen before include "Surly and unforthcoming" , "Sullen, crabby" , "Miserable" , "grouchy" , "Sullen or glum." .)