From time to time, whether working or not (2,3,3)
I believe the answer is:
on and off
'from time to time' is the definition.
(I've seen this before)
'whether working or not' is the wordplay.
I cannot really understand how this works, but
'working' could be 'on' and 'on' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for on and off that I've seen before include "From time to time, not continuously" , "periodically" , "Intermittently" , "From time to time, not continually" , "the two sides at Old Trafford?" .)