How do I solve 5 down in Daily Telegraph Cryptic 3372?

Question

Accepted Answer

5 down reads "Off and on, all that has come and gone?" (5,3,3,4 letters); the answer is EVERY NOW AND THEN. It's a cryptic definition: the whole clue is a playful or punny description of the answer. No wordplay decomposition to do — read laterally and identify what's being described. The full step-by-step breakdown is on this page.

Off and on, all that has come and gone? (5,3,3,4)

5D — Off and on, all that has come and gone? (5,3,3,4) — EVERY NOW AND THEN