Dare to take air by river (7)
I believe the answer is:
venture
'dare' is the definition.
(I've seen this before)
'air by river' is the wordplay.
'air' becomes 'vent' (both can mean to express or reveal).
'by' says to put letters next to each other.
'river' becomes 'ure' (river in Yorkshire).
'vent'+'ure'='VENTURE'
'to take' acts as a link.
(Other definitions for venture that I've seen before include "The undertaking involves uncertainty" , "Put at risk" , "Undertake a risky course of action" , "Dare to put forward" , "Proceed despite risk" .)