Crossword Genius

Great initial measures. Good ones (4)

Ross

I believe the answer is:

gems

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'good ones' is the definition.
Although both the answer and definition are plural nouns, I cannot understand how one could define the other.

'great initial measures' is the wordplay.
'initial' indicates taking the first letters.
'measures' becomes 'ems' (en is a unit of measurement used by printers).
The initial letter of 'great' is 'g'.
'g'+'ems'='GEMS'

Can you help me to learn more?

(Other definitions for gems that I've seen before include "Precious stones" , "Valuable stones" , "Jewels" .)

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