Rivers on both sides of university hospital in German region (4)
I believe the answer is:
ruhr
'german region' is the definition.
(I've seen this before)
'rivers on both sides of university hospital' is the wordplay.
'rivers' becomes 'rr' (an abbreviation for river written twice).
'on both sides of' indicates putting letters inside.
'university' becomes 'u' (abbreviation for university).
'hospital' becomes 'h' (abbreviation for hospital on maps).
'u'+'h'='uh'
'rr' going around 'uh' is 'RUHR'.
'in' is the link.
(Other definitions for ruhr that I've seen before include "Major industrial region of north-west Germany" , "German industrial area" , "Herman industrial area" , "Ger. industrial region" , "Rhine tributary, coal district" .)