Agree to see hospital dept on a case of sinusitis (6)
I believe the answer is:
assent
'agree to' is the definition.
(I've seen this before)
'hospital dept on a case of sinusitis' is the wordplay.
'hospital dept' becomes 'ENT' (Ear, Nose and Throat department).
'on' says to put letters next to each other.
'case of' means to remove the middle letters (outsides of).
'sinusitis' with its centre taken out is 'ss'.
'a'+'ss'='ass'
'ent' put after 'ass' is 'ASSENT'.
'see' is the link.
(Other definitions for assent that I've seen before include "Expression of agreement" , "Official sanction" , "Agree and concur" , "Acquiescence" , "Permit or approve" .)