Best do what in Spain and run? (7)
I believe the answer is:
conquer
'best' is the definition.
(I've seen this before)
'do what in spain and run?' is the wordplay.
'do' becomes 'con' (both can mean to defraud).
'what in spain' becomes 'que' ('what' in Spanish).
'and' says to put letters next to each other.
'run?' becomes 'r' (cricket abbreviation).
'con'+'que'+'r'='CONQUER'
(Other definitions for conquer that I've seen before include "Overcome, vanquish" , "Overcome by force" , "worst" , "Capture by force" , "Overwhelm by force" .)