Hard to put down in print in proper English (8)
I believe the answer is:
readable
I believe this is a double definition.
'hard to put down in print' is the first definition.
(as in a printed book said to be 'hard to put down')
'in proper english' is the second definition.
(as in intelligible or written correctly)
(Other definitions for readable that I've seen before include "Legible" , "can be studied" , "Like good book" , "Describing text" , "Fairly gripping" .)