The book on the lectern? (6)
I believe the answer is:
reader
'the book' is the definition.
(reader is a kind of book)
'on the lectern?' is the wordplay.
I cannot quite see how this works, but
'on' could be 're' (regarding) and 're' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for reader that I've seen before include "Peruser, of books perhaps" , "University lecturer; book of educational extracts" , "Peruser of texts" , "Interpreter of what is written" , "Learning book" .)