Irrational former official of Rome (6)
I believe the answer is:
pilate
'official of rome' is the definition.
The definition suggests a singular noun which matches the answer.
'irrational former' is the wordplay.
'irrational' becomes 'pi' (an irrational number).
'former' becomes 'late' (late can mean former or previous).
'pi'+'late'='PILATE'
Can you help me to learn more?
(Other definitions for pilate that I've seen before include "Roman who authorised the crufixion of Jesus" , "Magistrate passing death sentence" , "Pontius -, Roman procurator of Judaea" , "Biblical Roman procurator of Judaea" , "prefect" .)