Dish made from interlocking pieces mostly served in lit brandy (3,2,4)
I believe the answer is:
leg of lamb
'dish' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'interlocking pieces mostly served in lit brandy' is the wordplay.
'interlocking pieces' becomes 'Lego' (toy bricks).
'mostly' means to remove the last letter (most but not all of the word).
'served in lit brandy' becomes 'flambe' (flamb means cooked in spirits).
'flambe' with its last letter removed is 'flamb'.
'lego'+'flamb'='LEG OF LAMB'
'made from' acts as a link.
Can you help me to learn more?
(Other definitions for leg of lamb that I've seen before include "A Sunday roast?" , "meat" .)