Some ruler, a Jaipur prince (4)
I believe the answer is:
raja
'prince' is the definition.
(I've seen this in another clue)
'some ruler a jaipur' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'RAJA' is hidden in the letters of 'ruler a jaipur'.
(Other definitions for raja that I've seen before include "High Indian position" , "sovereign" , "Asian prince or king" , "Prominent Indian" , "Indian ruler" .)