Author of "Tristram Shandy" enters novel (6)
I believe the answer is:
sterne
'author of tristram shandy' is the definition.
(I've seen this in another clue)
'enters novel' is the wordplay.
'novel' indicates an anagram (letters in a new or novel order).
'enters' anagrammed gives 'STERNE'.
(Other definitions for sterne that I've seen before include "Writer" , "Laurence ---, novelist; sounds hard" , "Laurence ..., author of 'Tristram Shandy'" , "Irish-born novelist (A Sentimental Journey)" , "18th-century novelist" .)