Duty of sailor whenever visited by female (6)
I believe the answer is:
tariff
'duty' is the definition.
(I know that duty can be written as tariff)
'sailor whenever visited by female' is the wordplay.
'sailor' becomes 'tar' (tar can mean a sailor).
'whenever' becomes 'if' (if or when something happens).
'visited by' means one lot of letters go next to another.
'female' becomes 'f' (abbreviation).
'tar'+'if'+'f'='TARIFF'
'of' is the link.
(Other definitions for tariff that I've seen before include "List of duties on imports or exports" , "List of fixed charges as in hotels" , "List of prices or charges" , "Bill of fare" , "Export/import duty" .)