They have had to read, skipping, “Long, Long Ago” (3,4,3)

I believe the answer is:

the year dot

I'm a little stuck... Click here to teach me more about this clue!

'long ago' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for the year dot that I've seen before include "A very long time ago" , "The beginning of time (colloq.)" , "As long ago as can be remembered" , "date, one imagines" , "right at the start" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app