Serious complaint when boss's tie is undone (10)

I believe the answer is:

asbestosis

I'm a little stuck... Click here to teach me more about this clue!

'serious complaint' is the definition.
'asbestosis' can be an answer for 'complaint' (asbestosis is a kind of disease). I'm unsure of the 'serious' bit.

'when boss's tie is undone' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'is undone' indicates an anagram (the original order is undone).
'bosss'+'tie'='bossstie'
'bossstie' with letters rearranged gives 'bestosis'.
'as'+'bestosis'='ASBESTOSIS'

Can you help me to learn more?

(Another definition for asbestosis that I've seen is " Lung disease".)

I've seen this clue in The Independent.

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