Recommend writing about odd characters in plot (7)
I believe the answer is:
propose
'recommend' is the definition.
(thesaurus)
'writing about odd characters in plot' is the wordplay.
'writing' becomes 'prose' (I have seen 'Ordinary writing ' mean 'prose' so perhaps 'writing' could also mean 'prose').
'about' is an insertion indicator.
'odd characters in' means one should take alternating letters (the letters at odd-numbered positions).
The alternate letters of 'plot' are 'po'.
'prose' going around 'po' is 'PROPOSE'.
(Other definitions for propose that I've seen before include "advance" , "Intend" , "Put forward a plan" , "Put forward (motion)" , "Put forward for consideration" .)