Where, out East, smartly to cut the tail off a pony! (6)
I believe the answer is:
nippon
'where out east smartly' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'cut the tail off a pony' is the wordplay.
I cannot quite understand how this works, but
'cut' could be 'nip' (nipping is a kind of cutting) and 'nip' is located in the answer.
The remaining letters 'pon' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'to' is the link.
Can you help me to learn more?
(Other definitions for nippon that I've seen before include "Transliteration of "Japan"" , "Japanese name for Japan (6)" .)