Position so that niche is only seen at intervals (6)
I believe the answer is:
stance
'position' is the definition.
(stance is a kind of position)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for stance that I've seen before include "Attitude (of body, mind)" , "Bearing" , "Position of the body or an attitude" , "Way of standing, like golfer addressing ball" , "Position assumed by upright person" .)