Lad, go on overturned boat (7)
I believe the answer is:
gondola
'boat' is the definition.
(I've seen this before)
'lad go on overturned' is the wordplay.
'overturned' indicates an anagram.
'lad'+'go'+'on'='ladgoon'
'ladgoon' is an anagram of 'GONDOLA'.
(Other definitions for gondola that I've seen before include "Craft for Venetian canals" , "Venetian boat - airship car" , "Supermarket display unit" , "narrow boat" , "Venetian transport" .)