Endless danger for one of the little folk (4)
I believe the answer is:
peri
'one of the little folk' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'endless danger' is the wordplay.
'endless' means to remove the last letter.
'danger' becomes 'peril' (peril is a kind of danger).
'peril' with its final letter removed is 'PERI'.
'for' is the link.
Can you help me to learn more?
(Other definitions for peri that I've seen before include "Type of disembodied spirit or graceful young girl" , "Prefix denoting 'around'" , "Spirit of folklore" , "Fairy queen" , "Mythical being" .)