Bat welcome to devour rubbish (7)
I believe the answer is:
nictate
'bat' is the definition.
(I know that bat is a more specific form of nictate)
'welcome to devour rubbish' is the wordplay.
'welcome' becomes 'nice' (I can't explain this - if you can you should believe this answer much more).
'to devour' means one lot of letters goes inside another (inserted letters are swallowed or devoured).
'rubbish' becomes 'tat' (tat can mean rubbish or poor-quality material).
'nice' going around 'tat' is 'NICTATE'.
Can you help me to learn more?
(Other definitions for nictate that I've seen before include "shut their eyes momentarily" , "Wink" , "Blink - enact it (anag)" .)