Stain book, on the whole (4)
I believe the answer is:
blot
'stain' is the definition.
(synonyms)
'book on the whole' is the wordplay.
'book' becomes 'b' (abbreviation for book).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'the whole' becomes 'lot' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'b'+'lot'='BLOT'
Can you help me to learn more?
(Other definitions for blot that I've seen before include "Ink stain; disgrace" , "Dark mark or stain" , "Spot of ink, paint etc" , "bad mark" , "Ink mark" .)
