Base for the flying squad (7)
I believe the answer is:
'base for' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'flying squad' is the wordplay.
'flying' becomes 'air' (similar in meaning).
'squad' becomes 'port' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the' acts as a link.
Can you help me to learn more?
(Other definitions for airport that I've seen before include "Aerodrome" , "Fliers' terminus" , "landing here?" , "Heathrow or similar place" , "where flight begins or ends" .)