An excuse often picked early in bail (5)
I believe the answer is:
alibi
'an excuse' is the definition.
(excuse given by a suspect in an investigation)
'often picked early in bail' is the wordplay.
I cannot quite see how this works, but
an anagram of 'bail' is 'alib' which is within the answer.
A single letter 'i' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for alibi that I've seen before include "Story confirming innocence" , ""suspect's story"" , "Timely get-out" , "Cover story" , "Lawyer's weapon, Latin for 'elsewhere'" .)