The dog sat between two men (8)
I believe the answer is:
alsatian
'the dog' is the definition.
(alsatian is a kind of dog)
'sat between two men' is the wordplay.
'two men' means two substitutions for 'man'.
'between' indicates putting letters inside.
'man' becomes 'Al' (man's name).
'man' becomes 'ian' (man's name).
'al'+'ian'='alian'
'sat' put inside 'alian' is 'ALSATIAN'.
(Other definitions for alsatian that I've seen before include "Wolf-like dog" , "Old Frenchman" , "Large canine, may be police dog" , "Strong dog known as German Shepherd" , "Large dog and someone from Alsace" .)