It should be paid daily (gets 50% off) (6)
I believe the answer is:
charge
'it should be paid' is the definition.
(an amount to be paid)
'daily gets 50 off' is the wordplay.
'daily' becomes 'char' (both can mean a cleaner).
'50 off' indicates taking half (50 per cent of the letters taken off).
'gets' halved is 'ge'.
'char'+'ge'='CHARGE'
(Other definitions for charge that I've seen before include "rate" , "Lord Cardigan's order to his brigade" , "Formally accuse (someone)" , "Be aggressive" , "person in custody" .)