Gallery to become busy (4)
I believe the answer is:
gods
'gallery' is the definition.
(I've seen this in other clues)
'become busy' is the wordplay.
'become' becomes 'go' (eg to go rotten is to become rotten).
'busy' becomes 'ds' (I can't explain this - if you can you should give a lot more credence to this answer).
'go'+'ds'='GODS'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for gods that I've seen before include "high up in theatre" , "Supernatural beings" , "Idols" , "Area of theatre" , "objects of worship" .)