It's about time I am in credit with rising account (5)
I believe the answer is:
circa
'it's about' is the definition.
(I've seen this in another clue)
'in credit with rising account' is the wordplay.
'in' means one lot of letters goes inside another.
'credit' becomes 'cr' (abbreviation).
'with rising' becomes 'i' (I can't explain this - if you can you should believe this answer much more).
'account' becomes 'ca' (I've seen this in other clues).
'cr' going around 'i' is 'cir'.
'cir'+'ca'='CIRCA'
'time i am' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for circa that I've seen before include "Approximately (Lat.)" , "Approximately (Latin)" , "(Especially of a date) approximately" , "Approximately (of a year)" , "About, say, a date" .)