Reassure Sting and One Direction guarded by police department (8)
I believe the answer is:
convince
'reassure' is the definition.
The answer and definition can be both to do with communicating as well as being verbs in their base form.
Maybe there's an association between them I don't understand?
'sting and one direction guarded by police department' is the wordplay.
'sting' becomes 'con' (synonyms).
'and' means one lot of letters go next to another.
'one direction' becomes 'N' (N is an example).
'guarded by' means one lot of letters goes inside another.
'police department' becomes 'vice' (I am not sure about this - if you are sure you should believe this answer much more).
'n' put into 'vice' is 'vince'.
'con'+'vince'='CONVINCE'
Can you help me to learn more?
(Other definitions for convince that I've seen before include "Satisfy as to truth" , "Persuade successfully" , "Persuade someone of the truth of something" , "Bring round" , "Satisfy by evidence" .)