A test of bank's expansion team (4)

I believe the answer is:

exam

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'a test' is the definition.
('exam' can be a synonym of 'test')

I don't understand how the rest of the clue works.

(Other definitions for exam that I've seen before include "'Test, in short (4)'" , "Formal knowledge test" , "Students sit it" , "Student test" , "One might be taken for English" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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