Low on energy, as American cars may be (5)
I believe the answer is:
tired
'low' is the definition.
Both the answer and definition are adjectives. Maybe there's a link between them I don't understand?
'on energy as american cars may be' is the wordplay.
I cannot quite understand how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is present in the answer.
The remaining letters 'tid' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tired that I've seen before include "Ready to drop" , "Physically or mentally weary" , "Beat" , "In need of sleep" , "Exhausted" .)