Inexperience in cabinet periodically holding review (7)
I believe the answer is:
naivete
'inexperience' is the definition.
(I've seen this in another clue)
'in cabinet periodically holding review' is the wordplay.
'periodically' means one should take alternating letters (letters must be selected 'every so often').
'holding' is an insertion indicator.
'review' becomes 'vet' (I've seen this in other clues).
'in'+'cabinet'='incabinet'
The alternate letters of 'incabinet' are 'naie'.
'naie' enclosing 'vet' is 'NAIVETE'.
(Other definitions for naivete that I've seen before include "Being green" , "Lack of worldliness" , "Innocence, artlessness" , "Innocence or guillibility" , "Ingenuosity" .)