Duty gives way to enjoyment in special kind of railway (9)
I believe the answer is:
funicular
'kind of railway' is the definition.
'duty gives way to enjoyment in special' is the wordplay.
I cannot quite see how this works, but
'way' could be 'cul' (cul is a kind of way) and 'cul' is found in the answer.
'enjoyment' could be 'fun' (enjoyable activities) and 'fun' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for funicular that I've seen before include "Cable railway" , "(Of a railway) cable-operated" , "Railway up the side of a mountain" , "Using a cable" .)