Time is lost -- and energy -- producing list (7)
I believe the answer is:
itemise
'list' is the definition.
('list'->'itemize' is in my internal thesaurus and 'ize'->'ise')
'time is lost and energy' is the wordplay.
'lost' is an anagram indicator.
'and' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mc2).
'time'+'is'='timeis'
'timeis' is an anagram of 'itemis'.
'itemis'+'e'='ITEMISE'
'producing' is the link.
(Other definitions for itemise that I've seen before include "Using spell out" , "List exhaustively" , "Set down separately" , "specific" , "List each thing separately" .)