She can give us new heart (3)
I believe the answer is:
sue
'she' is the definition.
'give us new heart' is the wordplay.
'give' indicates an anagram (I've seen 'giving' mean this (the letters give the letters for another word)).
'heart' says to take the centre.
The central letter of 'new' is 'e'.
'us' with letters rearranged gives 'su'.
'su'+'e'='SUE'
'can' is the link.
(Other definitions for sue that I've seen before include "Prosecute at law" , "The girl to take to court" , "Use to take to court" , "Litigious girl" , "Bring charges against - girl" .)