empty luggage rack like this? (5,4)
I believe the answer is:
lower case
'rack like this?' is the definition.
The definition suggests a singular noun which matches the answer.
'empty luggage' is the wordplay.
'empty' becomes 'lower' (I can't explain this - if you can you should believe this answer much more).
'luggage' becomes 'case' (I've seen this in other clues).
'lower'+'case'='LOWER-CASE'
Can you help me to learn more?
(Other definitions for lower case that I've seen before include "What a baggage-handler might do" , "small type" , "Small, UNLIKE THIS!" , "in which I may never appear" , "Not in capital letters" .)