Endless danger for a fairy (4)
I believe the answer is:
peri
'fairy' is the definition.
(Persian mythological being)
'endless danger for a' is the wordplay.
'endless' indicates the central letters.
'danger' becomes 'raise' (raise is a kind of danger).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'a' becomes 'per' (eg 'one a day' means 'one per day').
The centre of 'raise' is 'i'.
'i' after 'per' is 'PERI'.
(Other definitions for peri that I've seen before include "Supernatural being in Persian folklore" , "A vision of loveliness" , "Ripe as a kind of fairy" , "Fairy of Persian folklore" , "Fairy queen" .)