Burning, a hollow across river (6)
I believe the answer is:
ardent
'burning' is the definition.
(both can mean passionate)
'a hollow across river' is the wordplay.
'hollow' becomes 'dent' (both can mean an impression or indentation).
'across' is an insertion indicator.
'river' becomes 'r' (abbreviation for river).
'a'+'dent'='adent'
'adent' going around 'r' is 'ARDENT'.
(Other definitions for ardent that I've seen before include "Passionate and glowing" , "full of zeal" , "Ranted badly and became earnest in love" , "Intensely enthusiastic" , "'Fervent, impassioned (6)'" .)