The two twits got in a hitman (8)
I believe the answer is:
assassin
'a hitman' is the definition.
(I've seen this before)
'the two twits got in' is the wordplay.
'the two' indicates the doubling of some letters.
'twits' becomes 'ass' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'got' says to put letters next to each other.
'ass' doubled is 'assass'.
'assass'+'in'='ASSASSIN'
Can you help me to learn more?
(Other definitions for assassin that I've seen before include "Hired killer" , "Political murderer" , "Political/religious killer" , "Paid killer" , "Liquidator" .)