Rise after start of day looking glum (5)
I believe the answer is:
drear
'looking glum' is the definition.
I can't judge whether this defines the answer.
'rise after start of day' is the wordplay.
'rise' becomes 'rear' (rearing is a kind of rising**).
'after' says to put letters next to each other.
'start of' says to take the initial letters.
The initial letter of 'day' is 'd'.
'rear' after 'd' is 'DREAR'.
Can you help me to learn more?
(Other definitions for drear that I've seen before include "gloomy in poem" , "grave" , "miserable" , "Cheerless (literary)" , "Gloomy and cheerless" .)