Happen at intervals (5)
I believe the answer is:
recur
(Other definitions for recur that I've seen before include "come back to one's mind" , "Happen again (5)" , "Persist" , "Return to mind" , "Happen again or repetitively" .)
I believe the answer is:
recur
(Other definitions for recur that I've seen before include "come back to one's mind" , "Happen again (5)" , "Persist" , "Return to mind" , "Happen again or repetitively" .)