Opening in banking appears (3)
I believe the answer is:
gap
'opening' is the definition.
(I know that opening can be written as gap)
'in banking appears' is the wordplay.
'in' indicates the answer is hidden within the clue.
'GAP' is hidden in the letters of 'banking appears'.
(Other definitions for gap that I've seen before include "Break, in a fence say" , "Disparity" , "Hiatus" , "Open space between two things, mind it" , "Interval, space" .)