Lots devoured by plump teenager (7)
I believe the answer is:
umpteen
'lots' is the definition.
(I've seen this before)
'devoured by plump teenager' is the wordplay.
'devoured by' indicates the answer is hidden within the clue.
'UMPTEEN' is hidden in the letters of 'plump teenager'.
(Other definitions for umpteen that I've seen before include "Numerous" , "Guarded" , "Large but indefinite number" , "Informally, very many" , "Quite a lot of (sl)" .)