Genuine; real (4)
I believe the answer is:
true
I believe this clue is a double definition.
'genuine' is the first definition.
(similar in meaning)
'real' is the second definition.
(similar in meaning)
(Other definitions for true that I've seen before include "not showing 12 [DISHONESTY]" , "Honest and straight" , "A false alternative?" , "Right - honourable" , "to be believed?" .)