Greed is a weakness, swallowing another case (7)
I believe the answer is:
avarice
'greed' is the definition.
(avarice is a kind of greed)
'a weakness swallowing another case' is the wordplay.
'weakness' becomes 'vice' (I've seen this before).
'swallowing' indicates putting letters inside.
'case' says to hollow out the word (remove centre letters).
'another' with its middle taken out is 'ar'.
'vice' going around 'ar' is 'varice'.
'a'+'varice'='AVARICE'
'is' acts as a link.
(Other definitions for avarice that I've seen before include "Cupidity" , "Wanting to be rich" , "Sway, control" , "Extreme greed for wealth" , "Greed for gain" .)