I find out the Spanish unbeliever (7)
I believe the answer is:
infidel
'unbeliever' is the definition.
(I know that unbeliever can be written as infidel)
'i find out the spanish' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'the spanish' becomes 'el' ('the' in Spanish).
'find' anagrammed gives 'nfid'.
'i'+'nfid'+'el'='INFIDEL'
(Other definitions for infidel that I've seen before include "Person who does not believe in a religion" , "One not believing" , "Person not operating in good faith" , "Person rejecting a specific religion" , "One without religion (mainly archaic)" .)