A roundabout way to come in (9)
I believe the answer is:
turnstile
'a roundabout' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'way to come in' is the wordplay.
'way' becomes 's' (Compass direction - South).
'to' becomes 'til' (I've seen this in another clue).
'come' becomes 'turne' (I can't explain this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
's'+'til'='stil'
'stil' put into 'turne' is 'TURNSTILE'.
Can you help me to learn more?
(Other definitions for turnstile that I've seen before include "Mechanical entry gate" , "gateway" , "Pivoting gate, to football grounds say" , "What controls access" , "Means of regulating passage" .)