Setting bail, one defence that might be offered (5)
I believe the answer is:
alibi
'defence that might be offered' is the definition.
'alibi' can be an answer for 'defence' (defence given to police by a suspect). I am not certain of the rest of the definition.
'setting bail one' is the wordplay.
'setting' is an anagram indicator.
'one' becomes 'i' (Roman numeral).
'bail' is an anagram of 'alib'.
'alib'+'i'='ALIBI'
Can you help me to learn more?
(Other definitions for alibi that I've seen before include "Defence against accusation - was seen elsewhere at the time" , "Excuse for failure" , "in order to prove I was elsewhere" , "Claim put to court" , "can offer a valid defence against most charges" .)