Involve hospital department facing trouble (6)
I believe the answer is:
entail
'involve' is the definition.
(thesaurus)
'hospital department facing trouble' is the wordplay.
'hospital department' becomes 'ent'.
'facing' says to put letters next to each other.
'trouble' becomes 'ail' ('ail' can be a synonym of 'trouble').
'ent'+'ail'='ENTAIL'
(Other definitions for entail that I've seen before include "Cut" , "Involve or require" , "legal restriction" , "Invlove or necessitate" , "Involve or make necessary" .)