One book by Sterne? Oddly, a different writer (5)
I believe the answer is:
ibsen
'writer' is the definition.
(Ibsen is an example)
'one book by sterne? oddly a different' is the wordplay.
'one' becomes 'i' (Roman numeral).
'book' becomes 'b'.
'by' is a charade indicator (letters next to each other).
'oddly' means one should take alternating letters.
'a different' indicates anagramming the letters.
The alternating letters of 'sterne' are 'sen'.
'b' after 'sen' is 'senb'.
'senb' anagrammed gives 'bsen'.
'i'+'bsen'='IBSEN'
(Other definitions for ibsen that I've seen before include "Norwegian dramatist of 'Hedda Gabler'" , "'Doll's House' playwright" , "Linesman" , "Norwegian playwright (Peer Gynt)" , "Norwegian dramatist and poet" .)