Fat tummy, big concern (11)
I believe the answer is:
corporation
I believe this is a double definition.
'fat tummy' is the first definition.
(informal term for belly fat)
'big concern' is the second definition.
(term for a large business or concern)
(Other definitions for corporation that I've seen before include "tummy" , "Big firm" , "Large firm" , "beer gut" , "Stomach" .)