Lost art, say, that's been restored (6)
I believe the answer is:
astray
'that's been restored' is the definition.
I can't tell whether this definition defines the answer.
'lost art say' is the wordplay.
'lost' indicates an anagram.
'art'+'say'='artsay'
'artsay' is an anagram of 'ASTRAY'.
Can you help me to learn more?
(Other definitions for astray that I've seen before include "Going wrong" , "Off the correct track" , "A satyr (anag.)" , "Gone off the right path" , "in the wrong place" .)