Welsh theatrical assistant? (7)

I believe the answer is:
dresser
This clue could be a double definition.
'welsh theatrical' is the first definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'assistant?' is the second definition.
(dresser is a kind of assistant)
Can you help me to learn more?
(Other definitions for dresser that I've seen before include "Piece of kitchen furniture" , "big chest" , "Lady's maid" , "Person working in one theatre" , "help in the theatre" .)
