With a shiner, look very angry (6)
I believe the answer is:
glower
'with a shiner look very angry' is the definition.
I know that 'angry' relates to this answer.
'look very angry' is the wordplay.
'look' becomes 'glow' (glowing is a kind of looking).
'very angry' becomes 'er' (I can't explain this - if you can you should believe this answer much more).
'glow'+'er'='GLOWER'
Can you help me to learn more?
(Other definitions for glower that I've seen before include "Stare angrily, scowl" , "Angry and sullen look" , "Look black" , "Look hard and angrily" , "Angry stare" .)