Five imps are turning into blood-suckers (8)
I believe the answer is:
vampires
'blood-suckers' is the definition.
I can't judge whether this defines the answer.
'five imps are turning' is the wordplay.
'five' becomes 'V' (Roman numeral).
'turning' is an anagram indicator.
'imps'+'are'='impsare'
'impsare' is an anagram of 'ampires'.
'v'+'ampires'='VAMPIRES'
'into' is the link.
Can you help me to learn more?
(Other definitions for vampires that I've seen before include "Night owls" , "Dracula's people" , "Blood-suckers like Dracula" .)