As usual, a carved Roman numeral (6)
I believe the answer is:
normal
'as usual' is the definition.
(I've seen this before)
'a carved roman numeral' is the wordplay.
'a carved' indicates an anagram.
'numeral' becomes 'l' (I am not sure about this - if you are sure you should believe this answer much more).
'roman' with letters rearranged gives 'norma'.
'norma'+'l'='NORMAL'
Can you help me to learn more?
(Other definitions for normal that I've seen before include "Usual - sane" , "Conforming to what is usual" , "Run-of-the-mill" , "Standard, expected" , "Unremarkable" .)