Salt limit Brown has admitted 'primarily idiotic' (7)
I believe the answer is:
captain
'salt' is the definition.
(salt can mean a sailor)
'limit brown has admitted primarily idiotic' is the wordplay.
'limit' becomes 'cap' (capping is a kind of limiting).
'brown' becomes 'tan' (tan is a kind of brown).
'has admitted' is an insertion indicator (admit can mean to bring in).
'primarily' indicates taking the first letters.
The initial letter of 'idiotic' is 'i'.
'tan' placed around 'i' is 'tain'.
'cap'+'tain'='CAPTAIN'
(Other definitions for captain that I've seen before include "One traditionally goes down with a sinking ship" , "Skip" , "Army rank" , "Chief" , "Lead (a team)" .)