Murder in the Spanish Main -- it involved Drake, ultimately (9)
I believe the answer is:
eliminate
'murder' is the definition.
(thesaurus)
'the spanish main it involved drake ultimately' is the wordplay.
'the spanish' becomes 'el'.
'involved' is an anagram indicator (involved can mean confusing or complex).
'ultimately' suggests the final letters.
The final letter of 'drake' is 'e'.
'main'+'it'='mainit'
'mainit' is an anagram of 'iminat'.
'el'+'iminat'+'e'='ELIMINATE'
'in' is the link.
(Other definitions for eliminate that I've seen before include "Do away with, remove" , "Murder" , "Completely remove, get rid of" , "Do away with, get rid of" , "waste" .)