Rolls-___ (5)
(Another definition for tumbles that I've seen is " Falls headlong, like Jill after Jack".)
'rolls' is the definition.
(I know this)
This is all the clue.
(Another definition for rosters that I've seen is " Schedules of times to be on duty".)
(Other definitions for royce that I've seen before include "Rolls' partner" , "25's partner" , "Charles Rolls's engineer partner Henry, d. 1933" .)