Reconnoitring a shell (6)
I believe the answer is:
casing
This might be a double definition.
'reconnoitring' is the first definition.
The definition and answer can be both to do with perception as well as being present participle verbs.
Perhaps there's a link between them I don't understand?
'a shell' is the second definition.
(I know that shell can be written as casing)
Can you help me to learn more?
(Other definitions for casing that I've seen before include "Outer covering of something" , "Outer protective covering" , "Recceing" , "This gives protection" , "Outside cover" .)