Grows fat like the rich (6)
I believe the answer is:
swells
'grows' is the definition.
(swelling is a kind of growing)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for swells that I've seen before include "Expands like posh people?" , "Inflates like posh people" , "BEcomes larger in volume, size or intensity" , "Grows larger like posh people" , "Becomes larger in size for posh people" .)