Deficient list loses nothing, but is not too heavy (8)
I believe the answer is:
portable
'loses nothing but is not too heavy' is the definition.
I can't judge whether this defines the answer.
'deficient list' is the wordplay.
'deficient' becomes 'por' (I am not sure about this - if you are sure you should believe this answer much more).
'list' becomes 'table' (list can mean a table or chart).
'por'+'table'='PORTABLE'
Can you help me to learn more?
(Other definitions for portable that I've seen before include "Maybe laptop" , "Able to be carried" , "radio" , "easy to bear?" , "to take with you" .)