Excuse one's given after jumping bail (5)
I believe the answer is:
alibi
'excuse' is the definition.
(excuse given by a suspect in an investigation)
'one's given after jumping bail' is the wordplay.
'one' becomes 'i' (Roman numeral).
'given after' is a charade indicator (letters next to each other).
'jumping' indicates anagramming the letters.
'bail' anagrammed gives 'alib'.
'i' after 'alib' is 'ALIBI'.
(Other definitions for alibi that I've seen before include "excuse given" , "Court evidence showing one was elsewhere" , "Evidence that the accused could not have been guilty" , "Proof one was elsewhere when crime was committed" , "Answer to charge - was somewhere else" .)