New love going wrong in book (5)
I believe the answer is:
novel
'book' is the definition.
(I know that novel is a type of book)
'new love going wrong in' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'going wrong' indicates an anagram.
'in' is an insertion indicator.
'love' is an anagram of 'ovel'.
'n' going into 'ovel' is 'NOVEL'.
(Other definitions for novel that I've seen before include "Fictitious prose work" , "Fictional work" , "Interestingly new; book" , "Kim, eg" , "New piece of fiction?" .)