Give a speech, primarily on robbery and tax evasion (5)
I believe the answer is:
orate
'give a speech' is the definition.
(oratory is public speaking)
'primarily on robbery and tax evasion' is the wordplay.
'primarily' suggests taking the first letters.
The initial letters of 'on robbery and tax evasion' is 'ORATE'.
(Other definitions for orate that I've seen before include "Make a formal address" , "Speak formally" , "Speaker may" , "Erato (anag.)" , "talk at length" .)