Their saloon replaced fuel (5,3,3)
I believe the answer is:
north sea oil
'fuel' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'their saloon replaced' is the wordplay.
'replaced' is an anagram indicator.
'their'+'saloon'='theirsaloon'
'theirsaloon' anagrammed gives 'NORTH SEA OIL'.
Can you help me to learn more?
(Other definitions for north sea oil that I've seen before include "Fuel obtained off British shores" , "Deep resource" .)