Possible Clues:

• Say one short greeting on the move
• Whole of Bury, say, is quarantined
• One perhaps needs to make a burial, laying in empty grave
• Whole number, e.g
• Whole unit, say, brought into Bury?
• Figure, say, included by artist omitting old man
• Number, say, occupying place in ground
• Number, say, being buried in Bury
• Bury keys inside one, for example?
• The first parts of 17- and 22-Across are always this, the first part of 46-Across is sometimes this, and the first part of 55-Across is never this