Ship commander's hat -- one with brown on the outside (7)
I believe the answer is:
captain
'ship commander's' is the definition.
'captain' can be an answer for 'commander's' (I've seen this before). I'm unsure of the 'ship' bit.
'hat one with brown on the outside' is the wordplay.
'hat' becomes 'cap' (cap is a type of hat).
'one with' is a charade indicator (letters next to each other).
'brown on the outside' becomes 'tain' (I am not sure about this - if you are sure you should believe this answer much more).
'cap'+'tain'='CAPTAIN'
Can you help me to learn more?
(Other definitions for captain that I've seen before include "American police officer" , "eg Hornblower" , "Lead (a team)" , "Naval commander" , "Army rank" .)