Only one seat between two men (5)
I believe the answer is:
sedan
'only one seat' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'two men' is the wordplay.
'two men' can mean two substitutions for 'man'.
'man' becomes 'se' (I can't justify this - if you can you should give a lot more credence to this answer).
'man' becomes 'dan'.
'se'+'dan'='SEDAN'
'between' acts as a link.
Can you help me to learn more?
(Other definitions for sedan that I've seen before include "Chair used as transport" , "A closed litter for one passenger" , "Chair to be carried by two" , "Where Prussians defeated French" , "Battle in 1940" .)