Tricky account is hard to keep in line (8)
I believe the answer is:
ticklish
'tricky' is the definition.
(thesaurus)
'account is hard to keep in line' is the wordplay.
'account' becomes 'tick' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'to keep in' indicates putting letters inside.
'line' becomes 'l' (used when specifying particular lines from a poem).
'tick'+'is'+'h'='tickish'
'tickish' going around 'l' is 'TICKLISH'.
Can you help me to learn more?
(Other definitions for ticklish that I've seen before include "(Of a problem) difficult to handle and requiring great tact" , "easy to get to laugh?" , "Sensitive to touch or requiring careful handling" , "hard to handle" , "Delicate - easily excited to laughter" .)