Ocean scanner is deployed for preliminary survey (14)
I believe the answer is:
reconnaissance
'preliminary survey' is the definition.
(I've seen this before)
'ocean scanner is deployed' is the wordplay.
'deployed' is an anagram indicator.
'ocean'+'scanner'+'is'='oceanscanneris'
'oceanscanneris' with letters rearranged gives 'RECONNAISSANCE'.
'for' is the link.
(Other definitions for reconnaissance that I've seen before include "Military observation" , "Scouting" , "Initial survey" , "Preliminary survey" .)