For the best reception, it needs real A1 adjustment (6)
I believe the answer is:
aerial
'adjustment' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for aerial that I've seen before include "imaginary" , "Radio waves receiver" , "Rod for receiving radio waves" , "Device to receive or transmit radio waves" , "Device for radio transmissions" .)