Rigid line taken by hospital department (9)
I believe the answer is:
stringent
'rigid' is the definition.
(thesaurus)
'line taken by hospital department' is the wordplay.
'line' becomes 'string' (string is a kind of line**).
'taken by' means one lot of letters go next to another.
'hospital department' becomes 'ent'.
'string'+'ent'='STRINGENT'
(Other definitions for stringent that I've seen before include "Strict, precise, exacting" , "binding" , "Of rule, say strict and precise" , "Uncompromising" , "tightly drawn" .)