Car company compresses hydrogen - a large fuel source (8)
I believe the answer is:
charcoal
'fuel source' is the definition.
'charcoal' can be an answer for 'fuel' (I've seen this before). I am not sure about the 'source' bit.
'car company compresses hydrogen a large' is the wordplay.
I cannot quite see how this works, but
an anagram of 'car' is 'arc' which is within the answer.
'hydrogen' could be 'h' (H is the chemical symbol for hydrogen) and 'h' is found within the answer.
'company' could be 'co' (abbreviation) and 'co' is found within the answer.
'a' is present in the answer.
'large' could be 'l' (eg in clothes sizes) and 'l' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for charcoal that I've seen before include "Fuel eg for barbecue" , "Fuel - stick for drawing" , "Very dark gray color" , "It's used in drawing and barbecues" , "What gets Barbie going" .)