A sign differs very largely (5)

I believe the answer is:

aries

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'a sign' is the definition.
(star sign)

I don't understand how the rest of the clue works.

(Other definitions for aries that I've seen before include "Philip -, English poet" , "A sign from Heaven" , "star group" , "Zodiacal sign also known as the Ram" , "Stars" .)

I've seen this clue in The Irish News.

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