Animatedly, auntie reads RLS adventure story (8,6)
I believe the answer is:
treasure island
'adventure story' is the definition.
(I've seen this before)
'animatedly auntie reads rls' is the wordplay.
'animatedly' is an anagram indicator (I've seen this in other clues).
'auntie'+'reads'+'rls'='auntiereadsrls'
'auntiereadsrls' is an anagram of 'TREASURE ISLAND'.
(Other definitions for treasure island that I've seen before include "Long John Silver tale" , "Robert Louis Stevenson novel" , "book - with 5a" , "Classic adventure story" , "R.L. Stevenson novel" .)