Academic by law revised clue in a big letter (9)

I believe the answer is:

majuscule

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

'big letter' is the definition.
'majuscule' can be an answer for 'letter' (thesaurus). I am not certain of the 'big' bit.

'academic by law revised clue' is the wordplay.
'academic' becomes 'ma'.
'by law' becomes 'jus' (I can't explain this - if you can you should believe this answer much more).
'revised' indicates anagramming the letters.
'clue' is an anagram of 'cule'.
'ma'+'jus'+'cule'='MAJUSCULE'

'in a' is the link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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