Naval officer to requisition one leaving base? (9)
I believe the answer is:
commander
'naval officer' is the definition.
(I've seen this before)
'requisition one leaving base?' is the wordplay.
'requisition' becomes 'commandeer' (I've seen this before).
'one leaving' is a deletion indicator.
'commandeer' with 'e' taken away is 'COMMANDER'.
'to' acts as a link.
(Other definitions for commander that I've seen before include "boss" , "Naval rank" , "The one who gives the orders" , "Naval officer" , "One hoping to be captain" .)