Cruise to the south of Cuba and America results in import tax (6)
I believe the answer is:
custom
'import tax' is the definition.
'custom' can be an answer for 'tax' (custom is a kind of tax). I am not certain of the 'import' bit.
'cruise to the south of cuba and america' is the wordplay.
'cruise' becomes 'tom' (actor Tom Cruise).
'to the south of' says to put letters next to each other (in a down clue, some letters go under others).
'cuba' becomes 'c'.
'and' is a charade indicator (letters next to each other).
'america' becomes 'US' (United States).
'c'+'us'='cus'
'tom' after 'cus' is 'CUSTOM'.
'results in' is the link.
Can you help me to learn more?
(Other definitions for custom that I've seen before include "Habitual action" , "Habitual patronage" , "Tradition; habit" , "Traditional usage" , "Accepted or habitual practice" .)