Gas extractable from methane only (4)
I believe the answer is:
neon
'gas' is the definition.
(neon is a gas)
'from methane only' is the wordplay.
'from' says the answer is hidden in the clue.
'NEON' is hidden in the letters of 'methane only'.
'extractable' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for neon that I've seen before include "Atomic number 10" , "Could it brighten proceedings" , "Sign gas" , "Gas - light" , "Brightly coloured advertising sign" .)