Intermittently (8)
'intermittently' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for on and off that I've seen before include "spasmodic" , "Switch choices" , "the two sides at Old Trafford?" , "Intermittently" , "Now and then, starting and stopping" .)
'intermittently' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for off and on that I've seen before include "Intermittently" , "Now and then, here and there (3, 3, 2)" , "the two sides at the Oval are this" , "Now and then, stop and start" , "Intermittent" .)
(Another definition for offandon that I've seen is " Occasionally".)