The Spanish have a balanced side (6)
I believe the answer is:
eleven
'side' is the definition.
(I've seen this before)
'the spanish have a balanced' is the wordplay.
'the spanish' becomes 'el' ('the' in Spanish).
'have' is a charade indicator (letters next to each other).
'a balanced' becomes 'even' (I've seen this in another clue).
'el'+'even'='ELEVEN'
(Other definitions for eleven that I've seen before include "Football or cricket team?" , "Football team; number" , "Number, on a team perhaps" , "Not first team (6,6) - See 24" , "Smallest positive three-syllable integer" .)