Kindly left European in revolutionary hospital department (7)
I believe the answer is:
lenient
'kindly' is the definition.
(thesaurus)
'left european in revolutionary hospital department' is the wordplay.
'left' becomes 'l' (common abbreviation).
'european' becomes 'e' (abbreviation e.g. EU).
'revolutionary' is a reversal indicator.
'hospital department' becomes 'ent'.
'in' backwards is 'ni'.
'l'+'e'+'ni'+'ent'='LENIENT'
(Other definitions for lenient that I've seen before include "Easy, soft" , "Tolerant, merciful" , "Mild and tolerant" , "Inclined to let people off lightly" , "Forbearing" .)