English variant changing say: true (7)
I believe the answer is:
estuary
'english variant' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'changing say true' is the wordplay.
'changing' indicates anagramming the letters.
'say'+'true'='saytrue'
'saytrue' is an anagram of 'ESTUARY'.
Can you help me to learn more?
(Other definitions for estuary that I've seen before include "Wide part of a river where it nears the sea" , "Weapon" , "Bristol Channel?" , "eg Thames, Humber" , "Here one comes close to the main" .)