Old naval commander’s spoken of Christmas holiday at sea? (5,4)
I believe the answer is:
'old naval commander's' is the definition.
(Marquis of Santa Cruz, Spanish admiral)
I don't understand the rest of the clue.
(Other definitions for santa cruz that I've seen before include "Chief town on La Palma" , "South American city" , "Tenerife's main city" , "Tenerife capital" , "Californian city" .)