A museum’s data, strangely, ultimately ignored one’s founder (6,7)
I believe the answer is:
madame tussaud
'one's founder' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'a museum's data strangely ultimately ignored' is the wordplay.
'strangely' indicates anagramming the letters.
'ultimately' says to take the final letters.
The last letter of 'ignored' is 'd'.
'a'+'museums'+'data'='amuseumsdata'
'amuseumsdata' anagrammed gives 'madametussau'.
'madametussau'+'d'='MADAME TUSSAUD'
(Other definitions for madame tussaud that I've seen before include "Swiss woman who modelled in London" , "her sculpture attempted realism" .)