The ill-tempered officer was promoted (6)
I believe the answer is:
morose
'the ill-tempered' is the definition.
(I've seen this before)
'officer was promoted' is the wordplay.
'officer' becomes 'mo' (I can't justify this - if you can you should give a lot more credence to this answer).
'was promoted' becomes 'rose' (I've seen this before).
'mo'+'rose'='MOROSE'
Can you help me to learn more?
(Other definitions for morose that I've seen before include "Sullen or glum." , "in a grumpy mood" , "Sullen, crabby" , "Silent, gloomy and ill-tempered" , "Moody, glum" .)