Looking glum, bury dog (7)
I believe the answer is:
pointer
'dog' is the definition.
(pointer is a kind of dog)
'looking glum bury' is the wordplay.
'looking glum' becomes 'po' (I can't explain this - if you can you should give a lot more credence to this answer).
'bury' becomes 'inter' (to inter is to put into the ground).
'po'+'inter'='POINTER'
Can you help me to learn more?
(Other definitions for pointer that I've seen before include "Game dog, used for its ability to scent" , "Sign" , "Hint (for a dog?)" , "Smooth-haired game-dog" , "helpful tip!" .)