Answer: shadowing

AnswerCrossword Clue
SHADOWINGTailing.
shadowingAccompany (someone) in their daily activities at work in order to gain experience at or insight into a job
shadowingEnvelop in shadow; cast a shadow over
shadowingSHADOW, to make dark or gloomy
shadowing(of an opposition politician) Be the counterpart of (a government minister or a ministry)
shadowingFollow and observe (someone) closely and typically secretly