The Spanish sovereign defeated contender (5)
I believe the answer is:
loser
'defeated contender' is the definition.
'the spanish sovereign' is the wordplay.
'the spanish' becomes 'los' ('the' in Spanish**).
'sovereign' becomes 'er' (Abbreviation for Elizabeth Regina).
'los'+'er'='LOSER'
(Other definitions for loser that I've seen before include "Failed competitor" , "One mislaying" , "Non-achiever" , "Roles for a non-winner" , "Unsuccessful contestant" .)