Section of account we excise as over-sentimental (4)
I believe the answer is:
twee
'over-sentimental' is the definition.
'section of account we excise' is the wordplay.
'section of' says the answer is hidden in the clue.
'TWEE' is hidden in the letters of 'account we excise'.
'as' is the link.
(Other definitions for twee that I've seen before include "Affectedly sweet" , "Excessively sentimental" , "Sentimentally sweet" , "Rather too pretty" , "Overly cute" .)