Gather it's a festival (7)
I believe the answer is:
harvest
'gather' is the definition.
(I know that harvest is a type of gather)
'it's a festival' is the wordplay.
I cannot really see how this works, but
'it's' could be 'es' ('e' can mean 'electronic' which is similar to 'IT') and 'es' is located in the answer.
'a' is within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for harvest that I've seen before include "Seasonal yield" , "seasonal collection" , "Process of gathering mature crops" , "Time to gather the crops" , "Gather in (a crop)" .)