Trade zip for pack's contents in obvious high camps (8)
I believe the answer is:
bivouacs
'camps' is the definition.
('bivouac' can be a synonym of 'camp')
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for bivouacs that I've seen before include "Temporary military camps" , "Temporary living quarters for soldiers" .)