Little Katharine found in dictionary that's approved (6)
I believe the answer is:
okayed
'approved' is the definition.
('okay' can be a synonym of 'approve')
'little katharine found in dictionary' is the wordplay.
'little katharine' becomes 'kay' (I've seen this in other clues).
'found in' indicates putting letters inside.
'dictionary' becomes 'oed' (Oxford English Dictionary).
'kay' put into 'oed' is 'OKAYED'.
'that's' is the link.
(Other definitions for okayed that I've seen before include "Sanctioned" , "Informally approved and agreed" , "Allowed" , "given thumbs up" , "Given the go-ahead" .)