Crossword Genius

Training inept GI forces — how long might it be? (5,2,6)

Ross

I believe the answer is:

piece of string

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'long might it be?' is the definition.
I can't tell whether this definition defines the answer.

'training inept gi forces' is the wordplay.
'training' indicates anagramming the letters (to train can mean to grow something into a shape).
'inept'+'gi'+'forces'='ineptgiforces'
'ineptgiforces' anagrammed gives 'PIECE OF STRING'.

'how' is the link.

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I've seen this clue in The Guardian.
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