a shadow of (oneself)
Someone or something that has changed dramatically to become decreased in vivacity in some way, often following negative circumstances or some traumatic event. Tom's been nothing but a shadow of himself since that accident, his bubbly, outgoing persona replaced by gloom and seriousness. The mass emigration of workers from the country during the recession has left it a mere shadow of itself.
*shadow of oneself
and *a shadow of itself; *a shadow of one's former selfFig. someone or something that is not as strong, healthy, full, or lively as before. (*Typically: be ~; become ~.) The sick man was a shadow of his former self. The abandoned mansion was merely a shadow of its old self.