Travelling abroad, Sam's a man on a mission (10)
I believe the answer is:
ambassador
'a man on a mission' is the definition.
I can't judge whether this definition defines the answer.
'travelling abroad sam's' is the wordplay.
'travelling' is an anagram indicator.
'abroad'+'sams'='abroadsams'
'abroadsams' with letters rearranged gives 'AMBASSADOR'.
Can you help me to learn more?
(Other definitions for ambassador that I've seen before include "diplomatic type" , "In a different case, he could be" , "Overseas envoy" , "High-ranking diplomat" , "accredited diplomat" .)