One consuming an apple (5)
I believe the answer is:
eater
I believe this clue is a double definition.
'one consuming' is the first definition.
(I've seen this before)
'apple' is the second definition.
(I've seen this before)
'an' acts as a link.
(Other definitions for eater that I've seen before include "Apple, perhaps" , "Consumer of food" , "Type of apple" , "One consuming" , "diner" .)