Whip is the Spanish leader of The House (4)
I believe the answer is:
lash
'whip' is the definition.
('lash' can be a synonym of 'whip')
'the spanish leader of the house' is the wordplay.
'the spanish' becomes 'las' ('the' in Spanish**).
'leader of' indicates taking the first letters.
The initial letter of 'house' is 'h'.
'las'+'h'='LASH'
'is' acts as a link.
(Other definitions for lash that I've seen before include "Fasten with rope; whip" , "Flog" , "cat hair?" , "Beat; fasten with cord" , "over the eye" .)