A book kept by unusual dealer, having merit as literature? (8)
I believe the answer is:
readable
'having merit as literature?' is the definition.
(easy or enjoyable to read)
'a book kept by unusual dealer' is the wordplay.
'book' becomes 'b' (abbreviation for book).
'kept by' is an insertion indicator.
'unusual' indicates an anagram.
'a'+'b'='ab'
'dealer' with letters rearranged gives 'readle'.
'ab' inserted into 'readle' is 'READABLE'.
(Other definitions for readable that I've seen before include "Descriptive of an interesting book or good handwriting" , "eye can interpret" , "okay as literature" , "Fairly gripping" , "Legible" .)