Rachel endlessly reviewed books inside Melody Maker (7)
I believe the answer is:
chanter
'melody maker' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'rachel endlessly reviewed books inside' is the wordplay.
'endlessly' means to remove the last letter.
'reviewed' indicates an anagram (letters reviewed or revised).
'books' becomes 'NT' (abbreviation for New Testament).
'inside' means one lot of letters goes inside another.
'rachel' with its final letter taken away is 'rache'.
'rache' with letters rearranged gives 'chaer'.
'chaer' enclosing 'nt' is 'CHANTER'.
Can you help me to learn more?
(Other definitions for chanter that I've seen before include "Pipe playing melody" , "Part of bagpipe" , "Pipe on set of bagpipes with finger-holes" , "Bagpipe melody pipe" .)