With soldiers invading, being in a complete state (8)

I believe the answer is:

entirety

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'complete state' is the definition.
'entirety' can be an answer for 'state' (entirety is a kind of state). I'm not certain of the 'complete' bit.

'with soldiers invading being' is the wordplay.
'with' indicates putting letters inside.
'soldiers' becomes 're' (Royal Engineers).
'invading being' becomes 'entity' (I've seen this in other clues. I am not sure about the 'invading' bit.).
're' placed within 'entity' is 'ENTIRETY'.

'in a' acts as a link.

Can you help me to learn more?

(Other definitions for entirety that I've seen before include "Absoluteness" , "The lot" , "Totality" , "Whole" , "Completeness" .)

I've seen this clue in The Times.

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