It’s great to be back from Gibraltar! (3)

I believe the answer is:

big

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'it's great' is the definition.
('big' can be a synonym of 'great')

I cannot understand how the remainder of the clue works.

(Other definitions for big that I've seen before include "oversized" , "Large or substantial" , "Important" , "Circus tent" , "Sizeable" .)

I've seen this clue in the Evening Standard.

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