The phrase "former shadow" typically refers to a person who used to be influential or powerful but is no longer in that position or role. It implies that the person's previous role or impact has faded away or diminished. Full definition
«People are very unhappy,» one former shadow minister said. (theguardian.com)
But he said it would also put pressure on former shadow ministers to put their differences aside and return to the top team. (mirror.co.uk)
Allegations of complicity by British security forces in the torture of Mr Mohamed came to light yesterday when they were presented to MPs by former shadow home secretary David Davis. (politics.co.uk)