Unknown in top pub, a very large rodent (8)

I believe the answer is:

capybara

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

'large rodent' is the definition.
(I've seen this before)

'unknown in top pub a' is the wordplay.
'unknown' becomes 'y' (algebra).
'in' is an insertion indicator.
'top' becomes 'cap' (cap is a kind of top**).
'pub' becomes 'bar' (I've seen this before).
'cap'+'bar'='capbar'
'y' placed within 'capbar' is 'capybar'.
'capybar'+'a'='CAPYBARA'

'very' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for capybara that I've seen before include "Pay a crab (anag) - rodent" , "largest animal of its kind" , "Largest rodent" , "Large South American rodent" .)

I've seen this clue in The Times.

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