Crossword Genius

Many a retiree, say, gets a bittern hatchling? (4,6)

Ross

I believe the answer is:

baby boomer

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

'retiree say gets a bittern hatchling?' is the definition.
I can't judge whether this defines the answer.

'many a' is the wordplay.
I cannot quite see how this works, but
'many' could be 'm' (Roman numeral for a thousand) and 'm' is present in the answer.
'a' is within the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Other definitions for baby boomer that I've seen before include "One of many born after WW2" , "Someone born in the decade after WWII" , "one arriving in a crowd" , "Person born shortly after WWII" , "born just after the war?" .)

I've seen this clue in The Guardian.
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