Somewhat open to return of Indian noble (4)
I believe the answer is:
ajar
'somewhat open' is the definition.
(I've seen this in another clue)
'return of indian noble' is the wordplay.
'return of' says the letters should be written backwards.
'indian noble' becomes 'raja' (I've seen this in another clue).
'raja' back-to-front is 'AJAR'.
'to' is the link.
(Other definitions for ajar that I've seen before include "partly opened" , "Not to answer" , "Half-closed" , "Part-open" , "Partially open" .)