Looking back, one law for the papers celebrated in India (6)
I believe the answer is:
diwali
'celebrated in india' is the definition.
The definition suggests a singular noun which matches the answer.
'looking back one law for the papers' is the wordplay.
'looking back' says the letters should be written in reverse.
'one' becomes 'i' (Roman numeral).
'for' says to put letters next to each other.
'the papers' becomes 'id' (identification papers).
'i'+'law'+'id'='ilawid'
'ilawid' written backwards gives 'DIWALI'.
Can you help me to learn more?
(Other definitions for diwali that I've seen before include "Festival in honour of Lakshmi" , "Indian festival" , "religious festival" , "Light festival" , "Hindu festival; I'd wail (anag.)" .)