What can be a sweet Polish horse with a shed outside hotel (7)
I believe the answer is:
rhubarb
'what can be a sweet' is the definition.
(a sweet or dessert might contain rhubarb)
'polish horse with a shed outside hotel' is the wordplay.
I cannot really see how this works, but
'horse' could be 'barb' and 'barb' is located in the answer.
'hotel' could be 'h' (phonetic alphabet: alpha, bravo, charlie etc.) and 'h' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for rhubarb that I've seen before include "perennial plant" , "mutterings in the theatre" , "Garden plant with reddish, edible stalks" , "The pinkish stalks are edible, but the leaves are poisonous" , "An edible red stalk" .)