A lieutenant lists first condiment (5,4)
I believe the answer is:
table salt
'condiment' is the definition.
(I've seen this before)
'a lieutenant lists first' is the wordplay.
'lieutenant' becomes 'lt' (abbreviation for lieutenant).
'lists' becomes 'tables' (I am not sure about this - if you are sure you should believe this answer much more).
'first' says to put letters next to each other.
'a'+'lt'='alt'
'alt' put after 'tables' is 'TABLE SALT'.
Can you help me to learn more?
(Other definitions for table salt that I've seen before include "contents of cellar" , "item on board" , "Condiment" , "white powder" , "Seasoning for meal" .)