State left royal horse in India (5)
I believe the answer is:
waler
'horse in india' is the definition.
The definition suggests a singular noun which matches the answer.
'state left royal' is the wordplay.
I cannot quite see how this works, but
'state' could be 'wale' (wale is a kind of state) and 'wale' is located in the answer.
'royal' could be 'r' (abbreviation) and 'r' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for waler that I've seen is " horse from overseas".)