Sun to rise on river? That's normal (7)
I believe the answer is:
natural
'normal' is the definition.
('natural' can be similar in meaning to 'normal')
'sun to rise on river?' is the wordplay.
'sun' becomes 'tan' (both can mean to get a sun tan).
'to rise' is a reversal indicator.
'on' is a charade indicator (letters next to each other).
'river?' becomes 'ural' (I've seen this before**).
'tan' written backwards gives 'nat'.
'nat'+'ural'='NATURAL'
'that's' is the link.
(Other definitions for natural that I've seen before include "Not artificial or man-made" , "Inborn; unaffected" , "Innate, inborn" , "Not artificial; off-white" , "Frank < , twenty-one" .)