In retrospect Indian food produces flatulence (3)
I believe the answer is:
gas
'flatulence' is the definition.
(flatulence is gas from the body)
'in retrospect indian food' is the wordplay.
'in' is an insertion indicator.
'retrospect indian' becomes 'gs' (I can't justify this - if you can you should believe this answer much more).
'food' becomes 'A' (A is an example).
'gs' going around 'a' is 'GAS'.
'produces' is the link.
Can you help me to learn more?
(Other definitions for gas that I've seen before include "Carbon dioxide, say" , "Eg, oxygen" , "American fuel" , "Chatter vapidly" , "Gossip" .)