More proficient part of cable railway (5)
I believe the answer is:
abler
'more proficient' is the definition.
(I've seen this before)
'part of cable railway' is the wordplay.
'part of' indicates a hidden word.
'ABLER' is hidden in the letters of 'cable railway'.
(Other definitions for abler that I've seen before include "fitter" , "The better" , "Increasingly smart" , "More proficient" , "More capable" .)