The phrase "welcome shot" generally means a small alcoholic drink that is offered to someone as a way to greet and make them feel welcome. Full definition
Our friendly staff is waiting to help you get the most out of Paris.Book with us and get a FREE welcome shot to be exchanged at our bar On the road pub. (hostelbookers.com)
Will Arsene Wenger dip into the market to give Arsenal's title challenge a welcome shot in the arm? (telegraph.co.uk)
2012 SCIENCE NEWS TOP 25: 2 Besieged by budget cuts and diminished by the end of the shuttle era, NASA got a welcome shot in the arm in August as mission controllers at the Jet Propulsion Laboratory in Pasadena, Calif., watched their latest interplanetary emissary guide itself to a safe landing on Mars. (sciencenews.org)