Almost eat too much, coming back for drink (4)
I believe the answer is:
grog
'drink' is the definition.
(grog is a kind of drink)
'almost eat too much coming back' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'eat too much' becomes 'gorge' (I've seen this before).
'coming back' is a reversal indicator.
'gorge' with its final letter removed is 'gorg'.
'gorg' written backwards gives 'GROG'.
'for' acts as a link.
(Other definitions for grog that I've seen before include "Drink of spirits mixed with water" , "Spirits and water mixture" , "Sailors' drink of rum and water" , "Mixture of spirit and water" , "The old sailor's tradition drink" .)