Unusual to tuck into great British fish with beef (9)

I believe the answer is:

grumbling

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'beef' is the definition.
(I know that grumbling is a type of complaint)

'unusual to tuck into great british fish' is the wordplay.
'unusual' becomes 'rum' (I've seen this before).
'to tuck into' means one lot of letters goes inside another.
'great' becomes 'G' (abbreviation in place names).
'british fish' becomes 'bling' (I can't justify this - if you can you should give a lot more credence to this answer).
'g'+'bling'='gbling'
'rum' inserted inside 'gbling' is 'GRUMBLING'.

'with' is the link.

Can you help me to learn more?

(Other definitions for grumbling that I've seen before include "Moaning" , "Grouchily complaining" .)

I've seen this clue in The Times.

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