Indian prince open when reflecting (4)
I believe the answer is:
raja
'indian prince' is the definition.
(I've seen this before)
'open when reflecting' is the wordplay.
'open' becomes 'ajar' (similar in meaning).
'when reflecting' says the letters should be written in reverse.
'ajar' in reverse letter order is 'RAJA'.
(Other definitions for raja that I've seen before include "Asian prince or king" , "Eastern leader" , "High Indian position" , "Prominent Indian" , "sovereign" .)