Actor originally put on Irish voice (3)
I believe the answer is:
air
'voice' is the definition.
(thesaurus)
'actor originally put on irish' is the wordplay.
'originally' indicates taking the first letters.
'put on' means one lot of letters go next to another.
'irish' becomes 'ir' (abbreviation).
The first letter of 'actor' is 'a'.
'a'+'ir'='AIR'
(Other definitions for air that I've seen before include "Spread publicity" , "that's inspired" , "Mixture of gases needed for breathing" , "Carriage" , "Dry; tune" .)