From time to time, 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)
'working or not' is the wordplay.
I cannot quite see how this works, but
'working' could be 'on' and 'on' is present in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' 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 "Perhaps switch positions" , "the two sides at Old Trafford?" , "Occasionally" , "Now and then, starting and stopping" , "periodically" .)