Erica's very hard sandwiches ruined tea (5)
I believe the answer is:
heath
'erica's' is the definition.
(I've seen this in another clue)
'very hard sandwiches ruined tea' is the wordplay.
'very hard' becomes 'hh' (I can't justify this - if you can you should believe this answer much more).
'sandwiches' means one lot of letters goes inside another (goes on either side like a sandwich).
'ruined' indicates anagramming the letters.
'tea' with letters rearranged gives 'eat'.
'hh' going around 'eat' is 'HEATH'.
Can you help me to learn more?
(Other definitions for heath that I've seen before include "Ex-Tory PM" , "Barren open land" , "Open uncultivated land" , "part of Hampstead" , "Ted - - (former PM)" .)