Drive one politician to the Spanish (5)
I believe the answer is:
impel
'drive' is the definition.
(I know this)
'one politician to the spanish' is the wordplay.
'one' becomes 'I' (Roman numeral).
'politician' becomes 'MP' (Member of Parliament).
'to the spanish' becomes 'el' ('the' in Spanish).
'i'+'mp'+'el'='IMPEL'
(Other definitions for impel that I've seen before include "'Drive, force (5)'" , "Hold together" , "Force forwards" , "Constrain" , "Urge or propel" .)