Approach plain with river (8)
I believe the answer is:
overture
'approach' is the definition.
(I know that approach can be written as overture)
'plain with river' is the wordplay.
'plain' becomes 'overt' (both can mean visible or obvious).
'with' means one lot of letters go next to another.
'river' becomes 'ure' (river in Yorkshire).
'overt'+'ure'='OVERTURE'
(Other definitions for overture that I've seen before include "Orchestral opener" , "Item of music" , "Introduction to, eg, an opera" , "eg 'The Hebrides'" , "Proposal" .)