Comedy duo in landau Harry led out (6,3,5)
I believe the answer is:
laurel and hardy
'comedy duo' is the definition.
(Stan Laurel and Oliver Hardy)
'landau harry led out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'landau'+'harry'+'led'='landauharryled'
'landauharryled' with letters rearranged gives 'LAUREL AND HARDY'.
'in' is the link.
(Other definitions for laurel and hardy that I've seen before include "Comedy stars" , "double act" , "clownish performers" .)