Repeal and reverse moon probes around early nineties (5)
I believe the answer is:
annul
'repeal' is the definition.
(synonyms)
'reverse moon probes around early nineties' is the wordplay.
'reverse' says the letters should be written backwards.
'moon probes' becomes 'luna' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'around' means one lot of letters goes inside another.
'early' suggests taking the first letters (I've seen 'earliest of' mean this).
The first letter of 'nineties' is 'n'.
'luna' enclosing 'n' is 'lunna'.
'lunna' back-to-front is 'ANNUL'.
'and' is the link.
Can you help me to learn more?
(Other definitions for annul that I've seen before include "Quash" , "Cancel, make void" , "scratch" , "Cancel officially" , "Cancel or render void" .)