ensañar
to be cruel
en-
to make, to put into
+
saña
fury, rage
Ensañar means to be cruel and can be thought of as en-0 (to make, to put into0) + saña1 (fury, rage1), literally meaning 'to put into a state of fury or rage'.
verb
  1. to be cruel
    To be cruel or vicious towards someone or something
    No debes ensañarte con los animales. // You shouldn't be cruel to animals.