I came in to ward off an evil spirit (5)
I believe the answer is:
fiend
'evil spirit' is the definition.
(I know that fiend is a type of evil spirit)
'i came in to ward off an' is the wordplay.
I cannot really see how this works, but
'i' is found in the answer.
'ward' could be 'fend' (as in warding or fending off an attacker) and 'fend' is located in the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for fiend that I've seen before include "Evil supernatural being" , "monster" , "addict" , "Devilish person" , "Devil" .)