To give her less would be cruel (4)
I believe the answer is:
ruth
'to give her less would' is the definition.
I can't tell whether this definition defines the answer.
'be cruel' is the wordplay.
'be' becomes 'rut' (rutting is a kind of being).
'cruel' becomes 'h' (I am not sure about this - if you are sure you should believe this answer much more).
'rut'+'h'='RUTH'
Can you help me to learn more?
(Other definitions for ruth that I've seen before include "- - Rendell, crime writer" , "Babe -, US baseball star" , "Girl's name; grief" , "Biblical woman" , "once felt for a Moabite woman" .)