Sailor is toady inviting in German eight, not English (9)
I believe the answer is:
yachtsman
'sailor' is the definition.
(yachtsman is a kind of sailor)
'toady inviting in german eight not english' is the wordplay.
I cannot really see how this works, but
'german eight' could be 'acht' (German translation of 'eight') and 'acht' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'is' is the link.
(Other definitions for yachtsman that I've seen before include "I may go round the world" , "sportsperson involved with rigging?" , "Member of sailing crew" , "Ainslie, for example" , "Male sailor" .)