Embark with earl after travelling? That’s odd (10)
I believe the answer is:
remarkable
'odd' is the definition.
(thesaurus)
'embark with earl after travelling?' is the wordplay.
'with' means one lot of letters go next to another.
'after travelling?' indicates anagramming the letters (letters travel around).
'embark' put after 'earl' is 'earlembark'.
'earlembark' anagrammed gives 'REMARKABLE'.
'that's' is the link.
(Other definitions for remarkable that I've seen before include "Extraordinary" , "surprising?" , "Striking" , "Noteworthy" , "unusual" .)