Rock back in a big way! (3)

I believe the answer is:

gib

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'rock' is the definition.
(both are nicknames for Gibraltar)

'back in a big way' is the wordplay.
'big' anagrams to 'GIB'.
But, I am unsure how the anagram is indicated.

Can you help me to learn more?

(Another definition for gib that I've seen is " The Rock".)

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