A number of sailors have to accept time in slum (10)
I believe the answer is:
shantytown
'slum' is the definition.
(shantytown is a kind of slum)
'a number of sailors have to accept time' is the wordplay.
'a number of sailors' becomes 'shanty' (I can't explain this - if you can you should give a lot more credence to this answer).
'have' becomes 'own' (to have something is to own it).
'to accept' means one lot of letters goes inside another.
'time' becomes 't' (abbreviation).
'shanty'+'own'='shantyown'
'shantyown' enclosing 't' is 'SHANTYTOWN'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for shantytown that I've seen before include "Deprived residential area" , "Collection of poor dwellings" , "Deprived area of very poor housing" , "area of ramshackle housing" , "Deprived urban area of run-down huts" .)