Noel Gallagher's finale welcomed by children first, then parents (9)

I believe the answer is:

christmas

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

'noel' is the definition.
(I know that noel can be written as Christmas)

'gallagher's finale welcomed by children first then parents' is the wordplay.
'finale' says to take the final letters.
'welcomed by' is an insertion indicator (letters welcomed inside).
'children' becomes 'ch' (genealogical abbreviation).
'first' becomes 'ist' (ist resembles mst).
'then parents' becomes 'mas' (ma is a kind of parent. I am not sure about the 'then' bit.).
The last letter of 'gallagher' is 'r'.
'ch'+'ist'='chist'
'r' inserted within 'chist' is 'christ'.
'christ'+'mas'='CHRISTMAS'

Can you help me to learn more?

(Other definitions for christmas that I've seen before include "and 24 Down: Last day of Advent calendar" , "Church festival" , "Winter festival" , "Not in general use" , "Religious festival" .)

I've seen this clue in The Telegraph.

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