Concealed indentures doesn't include DIRT (6)
I believe the answer is:
unseen
'concealed indentures doesn't include dirt' is the definition.
I can't judge whether this definition defines the answer.
'concealed indentures doesn't include dirt' is the wordplay.
'concealed' is an anagram indicator.
'doesn't include' indicates named letters should be taken away.
'indentures' with 'dirt' taken out is 'nenues'.
'nenues' with letters rearranged gives 'UNSEEN'.
Can you help me to learn more?
(Other definitions for unseen that I've seen before include "Concealed" , "Not noticed" , "Not detected" , "Passage for translation" , "Invisable" .)