Eat away in discreet Chinese restaurant (4)
I believe the answer is:
etch
'eat away' is the definition.
(I've seen this before)
'in discreet chinese restaurant' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ETCH' is hidden in the letters of 'discreet chinese restaurant'.
(Other definitions for etch that I've seen before include "Incribe" , "Make carvings" , "Engrave (glass/metal)" , "Draw on metal with acid" , "What most engravers presumably find easy to do" .)