Adult men below large openings (7)
I believe the answer is:
alcoves
'openings' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
'adult men below large' is the wordplay.
'adult' becomes 'a' (abbreviation).
'men' becomes 'coves' (I can't justify this - if you can you should believe this answer much more).
'below' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'large' becomes 'L' (eg in clothes sizes).
'coves' after 'l' is 'lcoves'.
'a'+'lcoves'='ALCOVES'
Can you help me to learn more?
(Other definitions for alcoves that I've seen before include "shady places" , "Small recesses in a larger room" , "set-back areas" .)