What’s in tea tent — to be this? (5)
I believe the answer is:
eaten
'this?' is the definition.
The answer and definition are not the same part of speech.
'what's in tea tent to' is the wordplay.
'what's in' says the answer is hidden in the clue.
'EATEN' is hidden within 'tea tent to'.
'be' acts as a link.
(Other definitions for eaten that I've seen before include "Upset" , "Devoured" , "Scoffed" , "having been fed?" , "Gobbled" .)