Was acquainted with novel, by the sound of it (4)
I believe the answer is:
knew
'was acquainted with' is the definition.
(I've seen this in another clue)
'novel by the sound of it' is the wordplay.
'novel' becomes 'new' (similar in meaning).
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'new' is a homophone of 'KNEW'.
(Other definitions for knew that I've seen before include "Was conscious of" , "Was cognisant or aware of" , "Understood" , "Had learnt; sounds like modern" , "Distinguished" .)