Commercial enterprise opening beside Yorkshire river (7)
I believe the answer is:
venture
'commercial enterprise' is the definition.
(venture is a kind of commercial enterprise)
'opening beside yorkshire river' is the wordplay.
'opening' becomes 'vent' (vent is a kind of opening).
'beside' says to put letters next to each other (I've seen this in other clues).
'yorkshire river' becomes 'ure' (I've seen this in other clues).
'vent'+'ure'='VENTURE'
(Other definitions for venture that I've seen before include "Undertaking that involves risk" , "Put at risk" , "Dare, take a chance" , "Risk or take a chance on" , "Commercial undertaking that risks a loss but promises a profit" .)