Chicken or game bird split down the back and grilled (10)
I believe the answer is:
spatchcock
I believe this is a double definition.
'chicken' is the first definition.
(I know that Spatchcock is a type of chicken)
'game bird split down the back and grilled' is the second definition.
(I've seen this before)
(Other definitions for spatchcock that I've seen before include "Inappropriately insert" , "Chicken split open and grilled - add a sentence or clause in an inappropriate place" , "game for getting heated?" , "cooked fowl" , "chicken on grill" .)