The Spanish king, a horny individual (3)
I believe the answer is:
elk
'a horny individual' is the definition.
(I know that elks are often horned)
'the spanish king' is the wordplay.
'the spanish' becomes 'el' ('the' in Spanish).
'king' becomes 'K' (abbreviation for king in chess).
'el'+'k'='ELK'
(Other definitions for elk that I've seen before include "Large ruminant" , "Large northern deer" , "Moose-like deer" , "American animal" , "Largest living deer" .)