Question

which words or phrase in the sentence provide the best clue to the meaning of the italicized word "expectantly" wagging their tails when they want to play. puppies will, wagging their tails, when they want to play, often sit

Answer 1

The clause "wagging their tails when they want to play" gives the best clue. In particular, "when they want to play" shows the puppies are waiting or expecting play, and "wagging their tails" is the behavior that shows that expectation.