I must have bits to eat (6)
I believe the answer is:
iodine
'i' is the definition.
(I is the chemical symbol for iodine)
'bits to eat' is the wordplay.
'bits' becomes 'io' (resembling 1 and 0, both bits in computing).
'to eat' becomes 'dine' (dining is a kind of eating).
'io'+'dine'='IODINE'
'must have' acts as a link.
(Other definitions for iodine that I've seen before include "Element forming black crystals or violet vapour" , "Element used in medicine, photography and dyes" , "Disinfectant made from seaweed" , "Mother-of-pearl" , "Infamous tablets in case of a nuclear emergency" .)