Pea is mushy and brown (5)

I believe the answer is:

sepia

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

'brown' is the definition.
(sepia is a kind of brown)

'pea is mushy' is the wordplay.
'pea is' anagrams to 'SEPIA'.
But, I'm not clear how this is indicated.

'and' is the link.

Can you help me to learn more?

(Other definitions for sepia that I've seen before include "Brown of old photos" , "tone of pictures?" , "Sort of ink" , "Sort of drawing" , "Brown tint" .)

I've seen this clue in The Sun.

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