Bad-tempered beagle raised poorly (12)
I believe the answer is:
disagreeable
'bad-tempered' is the definition.
(I've seen this before)
'beagle raised poorly' is the wordplay.
'poorly' indicates an anagram (a poor spelling).
'beagle'+'raised'='beagleraised'
'beagleraised' anagrammed gives 'DISAGREEABLE'.
(Other definitions for disagreeable that I've seen before include "Obnoxious" , "Bad-tempered" , "Unpleasant" , "Offensive - peevish" .)