Perhaps capital gains international transport (4)
I believe the answer is:
taxi
'transport' is the definition.
(taxi is a kind of transport)
'perhaps capital gains international' is the wordplay.
'perhaps capital gains' becomes 'tax' (capital gains tax is an example).
'international' becomes 'i' (abbreviation eg in IMF).
'tax'+'i'='TAXI'
(Other definitions for taxi that I've seen before include "Prepare to fly" , "Motor-cab" , "use apron" , "Transport for hire" , "Hackney carriage" .)