Transporting automobile by railway and paying only 50% (8)
I believe the answer is:
carrying
'transporting' is the definition.
('carry' can be a synonym of 'transport')
'automobile by railway and paying only 50' is the wordplay.
'automobile' becomes 'car' ('car' can be a synonym of 'automobile'**).
'by' says to put letters next to each other.
'railway' becomes 'ry' (abbreviation for railway).
'and' says to put letters next to each other.
'only 50' means to take half the letters (50 percent of the word is used).
'paying' cut in half is 'ing'.
'car'+'ry'+'ing'='CARRYING'
(Other definitions for carrying that I've seen before include "Conveying, transporting" , "Transmitting; transporting" , "Transporting - pregnant" , "providing freight service" , "Transporting, toting" .)