MUMBAI: Siddharth Kharat, who recently took voluntary retirement from service while posted as joint secretary in Mantralaya, on Tuesday joined Shiv Sena. He is likely to be the party’s candidate from Mehkar constituency in Buldhana district, a traditional Shiv Sena seat. Sena chief Uddhav Thackeray welcomed Kharat to the party at his residence, Matoshree. Sainath Tare, Kalyan district chief of …