Hearing vital flame is faint (4,4)
I believe the answer is:
keel over
'faint' is the definition.
(I've seen this before)
'hearing vital flame' is the wordplay.
I cannot really understand how this works, but
'flame' could be 'lover' (I've seen this in another clue) and 'lover' is found in the answer.
The remaining letters 'kee' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'is' is the link.
Can you help me to learn more?
(Other definitions for keel over that I've seen before include "Fall, as in a faint" , "Capsize" , "Pass out" , "Suddenly collapse" .)