Dead centre in open gorge (7)
I believe the answer is:
overeat
'gorge' is the definition.
('overeat' can be a synonym of 'gorge')
'dead centre in open' is the wordplay.
'centre' indicates the central letters.
'in' indicates putting letters inside.
'open' becomes 'overt' ('overt' is associated in meaning with 'open'**).
The middle of 'dead' is 'ea'.
'ea' put within 'overt' is 'OVEREAT'.
(Other definitions for overeat that I've seen before include "Consume too much food, stuff your stomach" , "Stuff oneself silly" , "Be gluttonous" , "Gobble to excess" , "Binge" .)