Dour airman’s displeased expression (7)

I believe the answer is:

grimace

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'displeased expression' is the definition.
'grimace' can be an answer for 'expression' (I've seen this before). I am not certain of the 'displeased' bit.

'dour airman's' is the wordplay.
'dour' becomes 'grim' (synonyms).
'airman' becomes 'ace' (flying ace).
'grim'+'ace'='GRIMACE'

Can you help me to learn more?

(Other definitions for grimace that I've seen before include "unpleasant expression" , "betray disgust" , "Nasty expression" , "Pained expression" , "Facial expression showing disgust, wry humour etc" .)

I've seen this clue in The Times.

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