Ambitious person has trouble with father over time (9)
I believe the answer is:
careerist
'ambitious person' is the definition.
(I've seen this before)
'trouble with father over time' is the wordplay.
'trouble with' becomes 'care'.
'father' becomes 'sire' ('sire' can be a synonym of 'father').
'over' says the letters should be written backwards.
'time' becomes 't'.
'sire' backwards is 'eris'.
'care'+'eris'+'t'='CAREERIST'
'has' is the link.
(Other definitions for careerist that I've seen before include "he wants to get on" , "Ambitious type" , "Maybe workaholic" , "Ambitious person" , "Ambitious worker" .)