What's up with trademark by an assassin? (3,3)
I believe the answer is:
hit man
'assassin?' is the definition.
(I've seen this before)
'what's up with trademark by an' is the wordplay.
'what's up with' becomes 'hi' (I can't justify this - if you can you should believe this answer much more).
'trademark' becomes 'tm' (abbreviation for trademark).
'by' says to put letters next to each other.
'hi'+'tm'+'an'='HIT-MAN'
Can you help me to learn more?
(Other definitions for hit man that I've seen before include "A modern paid assassin" , "In slang, a hired assassin" , "Liquidator" , "Hired murderer" , "A modern hired assassin" .)