Magnificent Dublin advertisement produced by old relative

I believe the answer is:

granddad

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'old relative' is the definition.
'granddad' can be an answer for 'relative' (granddad is a kind of relative). I am not certain of the 'old' bit.

'magnificent dublin advertisement produced by' is the wordplay.
'magnificent' becomes 'grand' (I've seen this before).
'dublin' becomes 'd' (this could be a standard abbreviation of which I'm unaware).
'advertisement' becomes 'ad' ('ad' can be a synonym of 'advertisement').
'produced by' is a charade indicator (letters next to each other).
'grand'+'d'+'ad'='GRANDDAD'

Can you help me to learn more?

(Another definition for granddad that I've seen is " Familiar old man".)

I've seen this clue in the Irish Times.

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