Light meat contains energy (6)
I believe the answer is:
beacon
'light' is the definition.
(I've seen this before)
'meat contains energy' is the wordplay.
I cannot quite understand how this works, but
'energy' could be 'ac' (AC is an example) and 'ac' is found in the answer.
The remaining letters 'beon' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for beacon that I've seen before include "Warning light on hill or cliff" , "guidance" , "Signal fire - transmitter" , "make light of it" , "Warning light on hilltop" .)