Drive one politician to take on the Spanish (5)
I believe the answer is:
impel
'drive' is the definition.
(I've seen this before)
'one politician to take on the spanish' is the wordplay.
'one' becomes 'i' (Roman numeral).
'politician' becomes 'MP' (Member of Parliament).
'to take on' means one lot of letters go next to another.
'the spanish' becomes 'el' ('the' in Spanish).
'i'+'mp'+'el'='IMPEL'
(Other definitions for impel that I've seen before include "Oblige" , "Urge forward, drive" , "Urge forward - push" , "Spur on" , "Force to act" .)