Language expert a millionaire employs (5)
I believe the answer is:
tamil
'language' is the definition.
(Tamil is an example)
'expert a millionaire employs' is the wordplay.
'employs' indicates a hidden word (I've seen 'employing' mean this (the answer is used or employed by the clue)).
'TAMIL' is hidden in the letters of 'expert a millionaire'.
(Other definitions for tamil that I've seen before include "Member of South Indian people" , "An official language of Sri Lanka" , "One in race" , "Southern Indian language" , "Native of south India or Sri Lanka" .)