A shed, or rail terminus at a seaside place (5)
I believe the answer is:
hovel
'a shed' is the definition.
(both can mean a basic outdoor building)
'rail terminus at a seaside place' is the wordplay.
I cannot really see how this works, but
'rail' could be 'el' (El train, short for elevated railway) and 'el' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'or' acts as a link.
Can you help me to learn more?
(Other definitions for hovel that I've seen before include "dump" , "Shack" , "wretched place" , "Ramshackle dwelling-place" , "Shanty; hut" .)