It will set about for example an old language (7)
I believe the answer is:
gelatin
'it' is the definition.
The definition suggests a singular noun which matches the answer.
'will set about for example an old language' is the wordplay.
'will' means one lot of letters go next to another (I've seen this in other clues).
'set about' shows that the letters should be reversed in order.
'for example' becomes 'e.g.' (short for 'exempli gratia', 'for example' in Latin).
'an old language' becomes 'Latin' (Latin is a dead language).
'eg' in reverse letter order is 'ge'.
'ge'+'latin' is 'GELATIN'.
Can you help me to learn more?
(Other definitions for gelatin that I've seen before include "Setter" , "Glue made from animal extracts" , "Colourless glue" , "Jelling agent" , "something gluey" .)