Given that the approach is about enabling the user to clear the search results faster . i'd recommend going with a Clear x call to action next to the breadcrumbs.
But is it really necessary to give multiple 'clear all's in the breadcrumb list.? If there are multiple categories of filters , we can just differentiate the categories in the breadcrumb bar with some subtle color differences and have a single clear all for the breadcrumbs.
Just my two cents :)
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