Not initially promoting treat? (6)
I believe the answer is:
outing
'treat?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for outing that I've seen before include "Jaunt" , "Day excursion" , "journey" , "Excursion as for picnic" , "Short pleasure trip" .)