Half the fight's getting husband to wash (4)
I believe the answer is:
bath
'wash' is the definition.
(bath is a kind of wash)
'half the fight's getting husband' is the wordplay.
'half the' indicates taking half.
'fight' becomes 'combat' (combat is a kind of fight).
'getting husband' becomes 'h' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'combat' cut in half is 'bat'.
'bat'+'h'='BATH'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for bath that I've seen before include "It may be run" , "Sit in it to wash" , "City where Persuasion ends" , "Large washtub - English city" , "Georgian city" .)