Undeterred by river, welcoming suggestions to go over (7)
I believe the answer is:
despite
'undeterred' is the definition.
(I've seen this before)
'river welcoming suggestions to go over' is the wordplay.
'river' becomes 'dee' (River Dee).
'welcoming' means one lot of letters goes inside another (in sense of 'inviting in').
'suggestions' becomes 'tips' (tip is a kind of suggestion).
'to go over' is a reversal indicator.
'tips' back-to-front is 'spit'.
'dee' enclosing 'spit' is 'DESPITE'.
'by' acts as a link.
(Other definitions for despite that I've seen before include "Notwithstanding" , "In the face" , "Regardless of, in defiance of" , "Without being affected by; contempt" , "Undeterred" .)