Repeat once more, only half botched (6)
I believe the answer is:
encore
'repeat' is the definition.
(I've seen this before)
'once more only half botched' is the wordplay.
'only half' indicates taking half.
'botched' indicates an anagram.
'more' with half the letters taken is 're'.
'once'+'re'='oncere'
'oncere' anagrammed gives 'ENCORE'.
(Other definitions for encore that I've seen before include "extra performance" , "Cry from the audience for more" , "Repeat performance, please" , "We need more" , "Audience call for another performance" .)