Snake found in a road or on a ship (6)
I believe the answer is:
aboard
'on a ship' is the definition.
(I've seen this before)
'snake found in a road' is the wordplay.
'snake' becomes 'boa' (boa constrictor, type of snake).
'found in' means one lot of letters goes inside another.
'road' becomes 'rd' (abbreviation).
'a'+'rd'='ard'
'boa' going within 'ard' is 'ABOARD'.
'or' is the link.
(Other definitions for aboard that I've seen before include "On (eg, a ship)" , "on a plane, perhaps" , "Joined for mutual benefit" , "On (a ship/plane)" , "Embarked on (a ship)" .)