Crew member considers missing hotel key (3,4)
I believe the answer is:
old salt
'crew member considers missing' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'hotel key' is the wordplay.
'hotel' becomes 'olds' (I can't explain this - if you can you should believe this answer much more).
'key' becomes 'alt' (the Alt keyboard button).
'olds'+'alt'='OLD SALT'
Can you help me to learn more?
(Other definitions for old salt that I've seen before include "Experienced sailor of saline sort" , "Experienced sailor with stale sodium chloride?" , "Seasoned sailor of mature years" , "'Ancient mariner (3,4)'" , "'Long-time sailor (3,4)'" .)