Become fluent in language as painter and decorator? (4,6)

'decorator?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'become fluent in language as painter and' is the wordplay.
I cannot really see how this works, but
'language' could be 'polish' (Polish is an example) and 'polish' is located in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
The remaining letters 'ail' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?