Service head devouring new Greek character's food (7)
I believe the answer is:
gnocchi
'food' is the definition.
(I have seen 'Starchy food' mean 'gnocchi' so perhaps 'food' could also mean 'gnocchi')
'service head devouring new greek character's' is the wordplay.
'service head' becomes 'goc' (abbreviation for General Officer Commanding).
'devouring' indicates putting letters inside.
'new' becomes 'n'.
'greek character' becomes 'chi' (letter from the Greek alphabet).
'goc' going around 'n' is 'gnoc'.
'gnoc'+'chi'='GNOCCHI'
(Other definitions for gnocchi that I've seen before include "Small dumplings used like pasta" , "A course in Rome" , "Italian potato dumplings" , "Italian dumpling made of potato, flour or semolina" , "simple meal?" .)