Fire department colour (3)

I believe the answer is:

red

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

'colour' is the definition.
(I know that red is a type of chromatic color)

'fire department' is the wordplay.
'RED' is hidden in amongst the letters.
However, I am uncertain how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for red that I've seen before include "Stop light" , "- - poker: Kniphofia" , "Colour of garnets" , "The colour of the former Russian army" , "Colour for danger" .)

I've seen this clue in the Evening Standard.

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