Norse god back in Benidorm (4)
I believe the answer is:
odin
'norse god' is the definition.
(I know that Odin is a norse god)
'back in benidorm' is the wordplay.
'back' shows that the letters should be reversed in order.
'in' indicates the answer is hidden within the clue.
'nido' is hidden within 'benidorm'.
'nido' reversed gives 'ODIN'.
(Other definitions for odin that I've seen before include "divine figure" , "who's worshipped" , "Scandinavian war god" , "The supreme Norse god and creator" , "Supreme god of war in Norse mythology" .)