German chap, one eating less? (6)
I believe the answer is:
dieter
I believe this is a double definition.
'german chap' is the first definition.
(common German name)
'one eating less?' is the second definition.
(someone on a diet)
(Other definitions for dieter that I've seen before include "German male" , "person who's determined to lose" , "The weight-watcher" , "one trying to lose weight" , "German fellow" .)