Traumatic to increase crossword output? (9)

I believe the answer is:

upsetting

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'traumatic' is the definition.

'increase crossword output?' is the wordplay.
'increase' becomes 'up' (upping is a kind of increasing).
'crossword output?' becomes 'setting' (I can't explain this - if you can you should give a lot more credence to this answer).
'up'+'setting'='UPSETTING'

'to' is the link.

Can you help me to learn more?

(Other definitions for upsetting that I've seen before include "Disturbing or upturning" , "Tipping" , "sad?" , "Alarming" , "worrying" .)

I've seen this clue in The Times.

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