A man on his own?
I believe the answer is:
tod
'a man' is the definition.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for tod that I've seen before include "Sly person" , "If you're on it, you're on your own" , "Former English weight for wool - dot it" , "Fox" , "One's alone on this" .)