Knowing of conflict within hospital department (5)
I believe the answer is:
aware
'knowing' is the definition.
(I've seen this before)
'conflict within hospital department' is the wordplay.
'conflict' becomes 'war' (war is a kind of conflict).
'within' indicates putting letters inside.
'hospital department' becomes 'ae' (A&E, Accident & Emergency).
'war' put within 'ae' is 'AWARE'.
'of' is the link.
(Other definitions for aware that I've seen before include "Conscious or having knowledge of" , "Knowing (of something)" , "Conscious, knowing about" , "well informed" , "Acquainted with or mindful of" .)