Eccentric named Ron having been sent back into custody (2,6)
I believe the answer is:
on remand
'having been sent back into custody' is the definition.
(I've seen this before)
'eccentric named ron' is the wordplay.
'eccentric' indicates anagramming the letters.
'named'+'ron'='namedron'
'namedron' is an anagram of 'ON REMAND'.
(Other definitions for on remand that I've seen before include "Not yet tried" , "officially not out" , "Status of some prisoners" , "awaiting court's decision?" , "Demon ran wild, being held in custody pending trial" .)