Sort of shirt for a slave, that's all (3,3)
I believe the answer is:
the lot
'all' is the definition.
(thesaurus)
'sort of shirt for a slave' is the wordplay.
'sort of shirt for' becomes 't' (I can't explain this - if you can you should give a lot more credence to this answer).
'a slave' becomes 'helot' (I've seen this before).
't'+'helot'='THE LOT'
'that's' is the link.
Can you help me to learn more?
(Other definitions for the lot that I've seen before include "Everything" , "goes under the hammer" .)