Live tours classy for D.Ross? (7)

I believe the answer is:
residue
'd ross?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'live tours classy' is the wordplay.
'live' becomes 'reside' (synonyms).
'tours' indicates putting letters inside (to tour can mean to go around).
'classy' becomes 'u' (U can mean upper class as in U- and non-U speech).
'reside' going around 'u' is 'RESIDUE'.
'for' is the link.
Can you help me to learn more?
(Other definitions for residue that I've seen before include "Remaining portion" , "Stuff left over" , "Leftovers" , "Matter left behind after other parts have been taken away" , "Remains to be seen" .)