Angry medic imbibing alcohol before end of day (6)
I believe the answer is:
grumpy
'angry' is the definition.
'medic imbibing alcohol before end of day' is the wordplay.
'medic' becomes 'gp' (general practitioner).
'imbibing' means one lot of letters goes inside another.
'alcohol' becomes 'rum' (rum is a kind of alcohol).
'before' means one lot of letters go next to another.
'end of' says to take the final letters.
The final letter of 'day' is 'y'.
'gp' placed around 'rum' is 'grump'.
'grump'+'y'='GRUMPY'
(Other definitions for grumpy that I've seen before include "Ill-tempered and crabby" , "Crabby and grouchy" , "animated little miner" , "Peevish" , "Gloomy and irritable like sour old man" .)