Surround doctor in rising river (5)
I believe the answer is:
embed
'surround' is the definition.
(I've seen this before)
'doctor in rising river' is the wordplay.
'doctor' becomes 'mb' (Bachelor of Medicine, Medicinae Baccalaureus).
'in' indicates putting letters inside.
'rising' is a reversal indicator (going up in a down clue).
'river' becomes 'dee' (River Dee).
'dee' back-to-front is 'eed'.
'mb' inserted within 'eed' is 'EMBED'.
(Other definitions for embed that I've seen before include "Fix fast in something solid" , "Fix firmly and deeply" , "the opposite of 19 [DEBUNK]?" , "Fix firmly in surrounding mass" , "Enclose snugly" .)