Powder room makes sleepyhead somehow appear dishevelled (4,1,4)

I believe the answer is:

look a mess

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'appear dishevelled' is the definition.
I can't judge whether this defines the answer.

'powder room makes sleepyhead somehow' is the wordplay.
'powder room' becomes 'loo' (I've seen this in another clue).
'sleepyhead' becomes 's' (head letter of 'sleepy').
'somehow' is an anagram indicator.
'makes'+'s'='makess'
'makess' with letters rearranged gives 'kamess'.
'loo'+'kamess'='LOOK A MESS'

Can you help me to learn more?

(Another definition for look a mess that I've seen is " appear untidy".)

I've seen this clue in The Guardian.

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