Hart ran to outbuilding but got beaten (8)
I believe the answer is:
thrashed
'beaten' is the definition.
('thrash' can be a synonym of 'beat')
'hart ran to outbuilding but' is the wordplay.
I cannot really understand how this works, but
an anagram of 'hart' is 'thra' which is present in the answer.
'outbuilding' could be 'shed' (outbuilding in a garden) and 'shed' is found within the answer.
No letters remain.
This explanation may well be incorrect...
'got' is the link.
Can you help me to learn more?
(Other definitions for thrashed that I've seen before include "given whitewashing" , "Beat soundly" , "Beat violently" , "Beaten soundly" , "severely punished" .)