Without covers, all told, vital novel (6)
I believe the answer is:
lolita
'novel' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
(Other definitions for lolita that I've seen before include "girl described by Nabokov" , "Nabokov's girl" , "Nabokov's nymphet" , "Precocious Nabokov heroine" , "Eponymous nymphette created in novel by Nabokov" .)