In the line, “a heart whose love is innocent! ” the word “heart” is used as sibilance metonymy personification synecdoche

I'd say synecdoche, which is basically a class of metonymy. Metonymy is when something related to the subject is used to represent it, like calling a businessman a "suit". Meanwhile, synecdoche is when a piece of the subject is used to represent the whole. In this case, the heart represents the person who is holding the love. Hope this helped.