Sit diner in mess: grub up! (8)

I believe the answer is:

disinter

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'grub up' is the definition.
Although both the answer and definition are verbs in their base form, I don't see how they can define each other.

'sit diner in mess' is the wordplay.
'in mess' indicates anagramming the letters.
'sit'+'diner'='sitdiner'
'sitdiner' with letters rearranged gives 'DISINTER'.

Can you help me to learn more?

(Other definitions for disinter that I've seen before include "Dig up something buried" , "Dig up, say a body" , "Bring up" , "Unearth" , "Exhume a body" .)

I've seen this clue in The Guardian.

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