Contemporary black fuel containing derv regularly (6)
I believe the answer is:
coeval
'contemporary' is the definition.
(I know that contemporary can be written as coeval)
'black fuel containing derv regularly' is the wordplay.
'black fuel' becomes 'coal' (coal is black).
'containing' indicates putting letters inside.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'derv' are 'ev'.
'coal' enclosing 'ev' is 'COEVAL'.
(Other definitions for coeval that I've seen before include "Having the same age or existing in same epoch" , "Contemporary in alcove" , "Of the same period -- alcove (anag)" .)