Packed, to be on the safe side (2,4)
I believe the answer is:
in case
I believe this is a double definition.
'packed' is the first definition.
(I've seen this before)
'to be on the safe side' is the second definition.
(Other definitions for in case that I've seen before include "for emergency" , "Where traveller may keep clothes" , "In order to allow for eventualities" , "As a precaution" , "For fear that" .)