Good book plausible on the surface (4)
I believe the answer is:
glib
'surface' is the definition.
Both the answer and definition are adjectives. Perhaps there's an association between them I don't understand?
'good book plausible on' is the wordplay.
'good' becomes 'g' (abbreviation).
'book' becomes 'b' (abbreviation for book).
'plausible' becomes 'li' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'on' says to put letters next to each other.
'b' after 'li' is 'lib'.
'g'+'lib'='GLIB'
'the' is the link.
Can you help me to learn more?
(Other definitions for glib that I've seen before include "Ready with insincere or superficial words" , "freedom of speech?" , "Silver-tongued" , "Superficially facile with words" , "Only superficially plausible" .)