Short study on good books leaves a mark (4)
I believe the answer is:
dent
'a mark' is the definition.
(I have seen 'Mark of knock ' mean 'dent' so perhaps 'mark' could also mean 'dent')
'short study on good books' is the wordplay.
'short' means to remove the last letter.
'study' becomes 'den' (term for a study or office).
'on' means one lot of letters go next to another.
'good books' becomes 'nt' (abbreviation for New Testament).
'den' with its final letter removed is 'de'.
'de'+'nt'='DENT'
'leaves' acts as a link.
(Other definitions for dent that I've seen before include "Slight damage" , "Surface hollow" , "Hollow from impact" , "Tend to small indentation" , "Injury to pride" .)