Supporter consuming large pie (4)
I believe the answer is:
flan
'pie' is the definition.
(I know that flan is a type of pie)
'supporter consuming large' is the wordplay.
'supporter' becomes 'fan' (fan is a kind of supporter).
'consuming' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'fan' going around 'l' is 'FLAN'.
(Other definitions for flan that I've seen before include "Open tart with a sweet or savoury filling" , "Open pastry case with savoury filling" , "Open pastry or sponge case with tasty filling" , "it may get jammed" , "Quiche" .)