Many-headed monster in Hardy novel (5)
I believe the answer is:
hydra
'many-headed monster' is the definition.
(I've seen this in another clue)
'hardy novel' is the wordplay.
'novel' is an anagram indicator (letters in a new or novel order).
'hardy' with letters rearranged gives 'HYDRA'.
'in' is the link.
(Other definitions for hydra that I've seen before include "Femme fatale of legend" , "Small red-berried tree" , "that regenerated after cuts at the top" , "Proliferating-head monster" , "Mythic monster with nine heads" .)