Involved boat company to smuggle cocaine plant (7)
I believe the answer is:
tobacco
'plant' is the definition.
(tobacco is a kind of plant)
'involved boat company to smuggle cocaine' is the wordplay.
'involved' is an anagram indicator (involved can mean confusing or complex).
'company' becomes 'co' (abbreviation).
'to smuggle' is an insertion indicator (smuggle can mean to secretly carry).
'cocaine' becomes 'C' (drugs abbreviation).
'co' enclosing 'c' is 'cco'.
'boat' with letters rearranged gives 'toba'.
'toba'+'cco'='TOBACCO'
(Other definitions for tobacco that I've seen before include "Smokable plant" , "New World product" , "American export" , "(Treated leaves of) American plant" , "Narcotic leaf plant" .)