Judge once concerned with one found guilty of stealing fruit (5)
I believe the answer is:
reeve
'judge once' is the definition.
(historical type of judge or magistrate)
'concerned with one found guilty of stealing fruit' is the wordplay.
'concerned with' becomes 're' (re can mean regarding, concerning).
'one found guilty of stealing fruit' becomes 'Eve' (Eve stole ate forbidden fruit).
're'+'eve'='REEVE'
(Other definitions for reeve that I've seen before include "Pass cable through narrow opening" , "High official" , "Chief magistrate, formerly" , "local official" , "[PILGRIM in the CANTERBURY TALES]" .)