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 see how this works, but
'flame' could be 'lover' (I've seen this in another clue) and 'lover' is found within the answer.
The remaining letters 'kee' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'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" .)
