Date inside with sailor, alien and DJ (6,6)
I believe the answer is:
dinner jacket
'date inside' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'sailor alien and dj' is the wordplay.
'sailor' becomes 'jack' (jack can informally mean a sailor).
'alien' becomes 'et' (extra terrestrial).
'and' is a charade indicator (letters next to each other).
'dj' becomes 'dinner' (I am not sure about this - if you are sure you should believe this answer much more).
'jack'+'et'='jacket'
'jacket' after 'dinner' is 'DINNER-JACKET'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for dinner jacket that I've seen before include "Man's formal garment" , "Formal male evening attire" , "Tuxedo" .)