Dreadful imp hears angels (8)
I believe the answer is:
seraphim
'angels' is the definition.
(seraph is a kind of angel)
'dreadful imp hears' is the wordplay.
'dreadful' indicates anagramming the letters.
'imp'+'hears'='imphears'
'imphears' is an anagram of 'SERAPHIM'.
(Other definitions for seraphim that I've seen before include "High-ranking angels" , "Angelic beings" , "Highest order of angels" , "Angels of the highest rank" , "High spirits" .)