Sailor saw a bit on travelling (9)
I believe the answer is:
boatswain
'sailor' is the definition.
(boatswain is a kind of sailor)
'saw a bit on travelling' is the wordplay.
'travelling' is an anagram indicator.
'saw'+'a'+'bit'+'on'='sawabiton'
'sawabiton' with letters rearranged gives 'BOATSWAIN'.
(Other definitions for boatswain that I've seen before include "Crew member" , "One at sea" , "In brief, he's a bosun" , "4 [TEMPEST] character" , "I was not AB (anag) - naval warrant officer" .)