There today, constructed a long time ago (3,4,3)
I believe the answer is:
the year dot
'a long time ago' is the definition.
I know nothing about this answer so I can't tell whether this works.
'there today constructed' is the wordplay.
'constructed' indicates anagramming the letters.
'there'+'today'='theretoday'
'theretoday' anagrammed gives 'THE YEAR DOT'.
Can you help me to learn more?
(Other definitions for the year dot that I've seen before include "Time's beginning" , "A very long time ago" , "right at the start" , "As long ago as can be remembered" , "date, one imagines" .)