Deity behind rain, to some extent (5)
I believe the answer is:
indra
'deity' is the definition.
(Indra is an example)
'behind rain to some extent' is the wordplay.
'to some extent' says the answer is hidden in the clue.
'INDRA' is hidden in the letters of 'behind rain'.
(Other definitions for indra that I've seen before include "Hindu god of rain and thunder - drain (anag)" , "Deity" , "Hindu sky god" , "Indian god" , "Hindu god of the weather" .)