Rogue on the Spanish force (5)
I believe the answer is:
impel
'force' is the definition.
('impel' can be a synonym of 'force')
'rogue on the spanish' is the wordplay.
'rogue' becomes 'imp'.
'on' is a charade indicator (letters next to each other).
'the spanish' becomes 'el'.
'imp'+'el'='IMPEL'
(Other definitions for impel that I've seen before include "Motivate" , "Force into motion" , "Make" , "Oblige" , "Urge or propel" .)