Idiotic lapse by current head of nursing in A&E (7)
I believe the answer is:
asinine
'idiotic' is the definition.
(thesaurus)
'lapse by current head of nursing in ae' is the wordplay.
'lapse' becomes 'sin' (I've seen this in other clues).
'by' is a charade indicator (letters next to each other).
'current' becomes 'i' (symbol for electric current).
'head of' says to take the initial letters.
'in' is an insertion indicator.
The initial letter of 'nursing' is 'n'.
'sin'+'i'+'n'='sinin'
'sinin' inserted inside 'ae' is 'ASININE'.
(Other definitions for asinine that I've seen before include "Stupid (as a donkey?)" , "Daft" , "Absurd" , "Foolish like donkey" , "Senseless" .)