Brutally taser mad Leo, first, and wild Olive (8)
I believe the answer is:
oleaster
'wild olive' is the definition.
(I've seen this in another clue)
'brutally taser mad leo first' is the wordplay.
I cannot really understand how this works, but
an anagram of 'taser' is 'aster' which is within the answer.
an anagram of 'leo' is 'ole' which is within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for oleaster that I've seen before include "Plant" , "One produces fruit" , "Tree" , "Shrub like an olive" , "Shrub; steel oar (anag.)" .)