Not much left but to change the title (6)
I believe the answer is:
little
'not much' is the definition.
(a small amount)
'left but to change the title' is the wordplay.
'left but' becomes 'l' (common abbreviation. I am not sure about the 'but' bit.).
'to change' is an anagram indicator.
'title' with letters rearranged gives 'ittle'.
'l'+'ittle'='LITTLE'
Can you help me to learn more?
(Other definitions for little that I've seen before include "Self-important authoritarian" , "Novel heroine born in the Marshalsea" , "Peanuts" , "Wee; minute" , "Not big, much or important" .)