Most of message received about high-class cosmetic (5)
I believe the answer is:
rouge
'cosmetic' is the definition.
(rouge is a kind of cosmetic)
'most of message received about high-class' is the wordplay.
'most of' means to remove the last letter.
'message received' becomes 'roger' (I've seen this before).
'about' indicates putting letters inside.
'high class' becomes 'u'.
'roger' with its final letter removed is 'roge'.
'roge' enclosing 'u' is 'ROUGE'.
(Other definitions for rouge that I've seen before include "Reddish cosmetic for colouring cheeks" , "Rumpled, disordered" , "See 1" , "Cheek colouring" , "Red cosmetic to colour cheeks" .)