As a crisp is transported, precariously (4-2-5)
I believe the answer is:
hand-to-mouth
'precariously' is the definition.
(I've seen this in another clue)
'as a crisp is transported' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hand-to-mouth that I've seen before include "With barely enough to exist" , "Just adequate (subsistence)" , "Precarious (existence)" , "Providing only bare essentials" .)