Message lab about a number of things (10)
I believe the answer is:
assemblage
'a number of things' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'message lab about' is the wordplay.
'about' indicates an anagram.
'message'+'lab'='messagelab'
'messagelab' is an anagram of 'ASSEMBLAGE'.
Can you help me to learn more?
(Other definitions for assemblage that I've seen before include "congregation" , "collection is made" , "Group" , "Collection, gathering" , "Collection (of things or people)" .)