Get rid of old hotel Basil ruined (7)
I believe the answer is:
abolish
'get rid of' is the definition.
(I know that get rid of can be written as abolish)
'old hotel basil ruined' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'ruined' indicates an anagram.
'o'+'h'+'basil'='ohbasil'
'ohbasil' anagrammed gives 'ABOLISH'.
(Other definitions for abolish that I've seen before include "Get rid of" , "Destroy" , "Do away with, rescind" , "Formally do away with" , "Put an end to, a rule perhaps" .)