Name in past given to soldiers, eg, The Great (7)

I believe the answer is:

agnomen

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'the great' is the definition.
I can't tell whether this defines the answer.

'name in past given to soldiers eg' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'in' indicates putting letters inside.
'past' becomes 'ago' (similar in meaning).
'given to' means one lot of letters go next to another.
'soldiers eg' becomes 'men' (soldier is a kind of man).
'n' inserted into 'ago' is 'agno'.
'agno'+'men'='AGNOMEN'

Can you help me to learn more?

(Other definitions for agnomen that I've seen before include "Roman extra name" , "Nickname" .)

I've seen this clue in The Times.

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