Had an effect before other changes up to now (8)

I believe the answer is:

hitherto

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'up to now' is the definition.
(I've seen this in another clue)

'had an effect before other changes' is the wordplay.
'had an effect before' becomes 'hit' (I am not sure about this - if you are sure you should believe this answer much more).
'changes' indicates an anagram.
'other' is an anagram of 'herto'.
'hit'+'herto'='HITHERTO'

Can you help me to learn more?

(Other definitions for hitherto that I've seen before include "So far" , "Up till now" , "Heretofore (8" , "Up to this point" , "Up to this time" .)

I've seen this clue in The Times.

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