A slice of beef is highly inappropriate food for vegetarian (4)

I believe the answer is:

fish

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

'inappropriate food for vegetarian' is the definition.
I can't tell whether this definition defines the answer.

'a slice of beef is highly' is the wordplay.
'a slice of' indicates a hidden word.
'FISH' is hidden within 'beef is highly'.

Can you help me to learn more?

(Other definitions for fish that I've seen before include "rock, perhaps" , "Aquatic creature(s)" , "Aquatic animal(s)" , "Search" , "Burbot or turbot, for example" .)

I've seen this clue in The Independent.

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