Screws not replaced in lookout's post (5-4)
I believe the answer is:
crows-nest
'screws not replaced in lookout's post' is the definition.
I can't judge whether this defines the answer.
'screws not replaced' is the wordplay.
'replaced' indicates anagramming the letters.
'screws'+'not'='screwsnot'
'screwsnot' anagrammed gives 'CROWS-NEST'.
Can you help me to learn more?
(Other definitions for crows-nest that I've seen before include "Ship lookout's position" , "Masthead lookout" , "Look-out platform on sailing ship, or black bird's home" , "Masthead platform" , "Ship's lookout point" .)