During period of prosperity, communist shows lack of interest (7)
I believe the answer is:
boredom
'lack of interest' is the definition.
(thesaurus)
'during period of prosperity communist' is the wordplay.
'during' means one lot of letters goes inside another.
'period of prosperity' becomes 'boom' (I've seen this before).
'communist' becomes 'red' (red is a kind of communist).
'boom' going around 'red' is 'BOREDOM'.
'shows' acts as a link.
(Other definitions for boredom that I've seen before include "Feeling" , "weary idleness" , "no interest" , "Mental state" , "Ennui in bedroom" .)