Crossword Genius

Concerned with ousting bad smell from fish tank component (6)

Ross

I believe the answer is:

turret

'tank component' is the definition.
(part of a military tank)

I cannot understand how the rest of the clue works.

(Other definitions for turret that I've seen before include "One of two rings" , "Small tower projecting from a wall of a castle" , "Armoured tower" , "Small tower on defensive wall - or tank" , "Small corner tower" .)

I've seen this clue in The Times.
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