Not a friendly visit made by a bugler (4,4)

'not a friendly' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'visit made by a bugler' is the wordplay.
'visit' becomes 'call' (call is a kind of visit).
'made by' says to put letters next to each other (letters written or made by another set of letters).
'a bugler' becomes 'duty' (I can't justify this - if you can you should believe this answer much more).
'call' put after 'duty' is 'DUTY CALL'.

Can you help me to learn more?