Bank or row (4)
I believe the answer is:
tier
I believe this clue is a double definition.
'bank' is the first definition.
(both can mean a row of similar things)
'row' is the second definition.
(a tier is a row of things)
(Other definitions for tier that I've seen before include "this person secures" , "One who secures" , "Level of a structure" , "'Level, grade (4)'" , "Hierarchical level" .)