International organisation faded, we hear — that's natural (6)
I believe the answer is:
undyed
'natural' is the definition.
(similar in meaning)
'international organisation faded we hear' is the wordplay.
'international organisation' becomes 'UN' (United Nations).
'faded' becomes 'died' (I've seen this before).
'we hear' shows a homophone (sound like).
'un'+'died'='undied'
'undied' sounds like 'UNDYED'.
'that's' is the link.
(Other definitions for undyed that I've seen before include "Not coloured" , "Without artificial colouring" .)