Scoundrel wearing fedora scales wall surreptitiously (6)

I believe the answer is:

rascal

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

'scoundrel' is the definition.
(I know that rascal is a type of scoundrel)

'wearing fedora scales wall surreptitiously' is the wordplay.
'RASCAL' is hidden in amongst the letters.
But, I'm unsure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for rascal that I've seen before include "naughty child" , "Knave, rogue" , "A mischievous and maybe dishonest person" , "Reprobate" , "Mischievous person or confused lascar" .)

I've seen this clue in The Irish Times.

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