Without fail, greaser will provide crude transport (3,6)
I believe the answer is:
oil tanker
'without fail greaser will' is the definition.
I can't tell whether this defines the answer.
'crude transport' is the wordplay.
'crude' becomes 'oil' (I've seen this before).
'transport' becomes 'tanker' (tanker is a kind of transport).
'oil'+'tanker'='OIL-TANKER'
'provide' is the link.
Can you help me to learn more?
(Other definitions for oil tanker that I've seen before include "[See] ocean-going vessel" , "craft" , "Ship carrying "black gold"" , "Fuel transporter" , "On which crude" .)