Crossword Genius

Supplementary membership fees cover one journal (10)

Ross

I believe the answer is:

subsidiary

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

'supplementary' is the definition.
(I know that supplementary can be written as subsidiary)

'membership fees cover one journal' is the wordplay.
'membership fees' becomes 'subs' (fees paid to a club or organisation).
'cover one' becomes 'i' (I can't justify this - if you can you should believe this answer much more).
'journal' becomes 'diary' (synonyms).
'subs'+'i'+'diary'='SUBSIDIARY'

Can you help me to learn more?

(Other definitions for subsidiary that I've seen before include "Contributory" , "company" , "Less important" , "of lesser importance" , "Minor" .)

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