Show how novel is biographical reference (4,3)
I believe the answer is:
whos who
'biographical reference' is the definition.
(Who's Who is a biographical reference work)
'show how novel' is the wordplay.
'novel' indicates an anagram (letters in a new or novel order).
'show'+'how'='showhow'
'showhow' is an anagram of 'WHOS WHO'.
'is' acts as a link.
(Other definitions for whos who that I've seen before include "only important ones here" , "people get in here when famous" , "Top people's directory" , "Celebrities' reference book" , "Lexicon or VIPs" .)