He's Spanish, so Norse would only confuse him (5)
I believe the answer is:
senor
'he's spanish' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'norse would only confuse him' is the wordplay.
'norse' can be anagrammed to 'SENOR'.
But, I'm unsure how the anagram is indicated.
'so' acts as a link.
Can you help me to learn more?
(Other definitions for senor that I've seen before include "way of addressing Figaro, say" , "Spanish title" , "Title of a Spanish-speaking man" , "Norse (anag.)" , "Mister in European country" .)