Eat away, seeing bar in centre (7)
I believe the answer is:
corrode
'eat away' is the definition.
(I've seen this before)
'bar in centre' is the wordplay.
'bar' becomes 'rod' (I've seen this in other clues**).
'in' is an insertion indicator.
'centre' becomes 'core' (core is a kind of centre).
'rod' inserted within 'core' is 'CORRODE'.
'seeing' is the link.
(Other definitions for corrode that I've seen before include "Cause to rust" , "Growth in hazel buds" , "Eg, to rust" , "Chemically weaken" , "Slowly eat" .)