Starts to order in lighter fuel (3)
I believe the answer is:
oil
'fuel' is the definition.
(I've seen this before)
'starts to order in lighter' is the wordplay.
'starts to' indicates taking the first letters.
The first letters of 'order in lighter' is 'OIL'.
(Other definitions for oil that I've seen before include "What can be extracted" , "painting" , "Liquid fuel" , "eg Olive" , "Crude" .)