Back to find eastern record established as the most profound (7)
I believe the answer is:
deepest
'the most profound' is the definition.
(I've seen this in another clue)
'back to find eastern record established' is the wordplay.
'back to' indicates one should take the final letters.
'eastern' becomes 'e'.
'record' becomes 'ep' (abbreviation for extended play record).
'established' becomes 'est' (abbreviated used in shop signs).
The final letter of 'find' is 'd'.
'd'+'e'+'ep'+'est'='DEEPEST'
'as' acts as a link.
(Other definitions for deepest that I've seen before include "Profoundest" , "hardest to understand" , "Most intense" , "most demanding" , "Most profound" .)