Small balls in position one doesn't want to lose (8)
I believe the answer is:
bearings
I believe this clue is a double definition.
'small balls' is the first definition.
(ball bearings)
'position one doesn't want to lose' is the second definition.
(to lose your bearings is to get lost)
'in' is the link.
(Other definitions for bearings that I've seen before include "Direction relative to N." , "Part of machine" , "(One's) orientation" , "(Sense of) one's position or direction" , "Moving parts; directions" .)