This circus somehow gets backing for a festival (6,7)
I believe the answer is:
corpus christi
'a festival' is the definition.
(I've seen this before)
'this circus somehow gets backing for' is the wordplay.
'somehow' indicates anagramming the letters.
'gets' means one lot of letters goes inside another (gets can mean captures or absorbs).
'backing' says the letters should be written in reverse.
'for' becomes 'pro' (I've seen this before).
'pro' written backwards gives 'orp'.
'this'+'circus'='thiscircus'
'thiscircus' is an anagram of 'cuschristi'.
'cuschristi' going around 'orp' is 'CORPUS CHRISTI'.
(Other definitions for corpus christi that I've seen before include "Texan city: name shared by colleges at Oxford and Cambridge" , "Oxbridge college" , "Oxford or Cambridge college" , "Church festival; Oxford college" .)