Lost as a dog may be (6)
I believe the answer is:
astray
'lost' is the definition.
(synonyms)
'as a dog may be' is the wordplay.
'a dog may be' becomes 'tray' (I am not sure about this - if you are sure you should believe this answer much more).
'as'+'tray'='ASTRAY'
Can you help me to learn more?
(Other definitions for astray that I've seen before include "Up the garden path?" , "Off one's route or lost" , "Off target" , "In a lost state" , "Wandering off the track" .)