Almost choke CO? (3)
I believe the answer is:
gas
'almost choke co?' is the definition.
I can't judge whether this defines the answer.
'almost choke' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'choke' becomes 'gasp' (I've seen this in another clue).
'gasp' with its final letter removed is 'GAS'.
Can you help me to learn more?
(Other definitions for gas that I've seen before include "eg CO2" , "idle chit-chat" , "Substance like air" , "Fumes, vapour" , "Chat (colloq.)" .)