The most common and most likely answer to this crossword clue is the 10 letter word COAL-FIRED
I've seen this crossword clue in Financial Times
C
O
A
L
-
F
I
R
E
D
Buddy explains!
The straight part
We know that "Fossil-fuel dependent" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fossil-fuel dependent = coal-fired.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does COAL-FIRED mean?
COAL-FIRED adjective- Fired with coal.