Where constellations can be seen over Oz on acid trip (6)
I believe the answer is:
zodiac
'where constellations can be seen' is the definition.
The answer is a location as well as being a singular noun. This is suggested by the definition.
'oz on acid trip' is the wordplay.
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'trip' indicates an anagram.
'oz'+'acid'='ozacid'
'ozacid' anagrammed gives 'ZODIAC'.
'over' acts as a link.
Can you help me to learn more?
(Other definitions for zodiac that I've seen before include "17 Across is a sign of the ......." , "Horoscope diagram" , "Set of star signs" , "Twelve-sign belt" , "Heavenly area" .)