Skilful, holding account over, in effect (2,5)
I believe the answer is:
de facto
'in effect' is the definition.
('de facto' can be a synonym of 'in effect')
'skilful holding account over' is the wordplay.
'skilful' becomes 'deft' (I've seen this before).
'holding' is an insertion indicator.
'account' becomes 'ac'.
'over' becomes 'o' (cricket abbreviation**).
'deft' enclosing 'ac' is 'defact'.
'defact'+'o'='DE FACTO'
(Other definitions for de facto that I've seen before include "Really" , "In reality, actual" , "effective" , "In fact (whether by right or not)" , "In practice" .)