The most common and most likely answer to this crossword clue is the 9 letter word PERISCOPE
I've seen this crossword clue in The Times
P
E
R
I
S
C
O
P
E
More clues leading to the result PERISCOPE
- It helps helmsman manage after risks leaving loch
- Son wearing fairy cloak that gives a superior look
- Recipe sop cooked up for looker in the Navy
- Bent coppers i.e. people in deep may be shown up by this
- Means of oversight for every single police officer in the Home Counties
- One’s always up for a sea view
- It helps sub manage risks going first out of loch
- One for takng a view from below
- What may help little person to see fairy’s garment
- Aid which helps you see pier and copse if blurred
Buddy explains!

The straight part
We know that "looker in the Navy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case looker in the navy = periscope.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does PERISCOPE mean?
PERISCOPE noun- A form of viewing device that allows the viewer to see things at a different height level and usually with minimal visibility.
- : A general or comprehensive view.
- To rise and peer around, in the manner of a periscope.
- To broadcast live video stream using Periscope app via phone or tablet.