Choose to keep current dispatch for Mars? (7)
I believe the answer is:
deicide
'dispatch for mars?' is the definition.
(deicide is killing a god eg the Roman god Mars)
'choose to keep current' is the wordplay.
'choose' becomes 'decide' (I've seen this before).
'to keep' means one lot of letters goes inside another.
'current' becomes 'I' (symbol for electric current).
'decide' going around 'i' is 'DEICIDE'.
(Other definitions for deicide that I've seen before include "divine crime" , "dispatch for Mars, say" , "Killer" , "Killing of divine being" , "Most unholy of sins" .)