Simpleton in Djibouti occasionally (5)
I believe the answer is:
idiot
'simpleton' is the definition.
(I know that idiot is a type of simpleton)
'in djibouti occasionally' is the wordplay.
'occasionally' means one should take alternating letters.
'in'+'djibouti'='indjibouti'
The alternate letters of 'indjibouti' are 'IDIOT'.
(Other definitions for idiot that I've seen before include "Dipstick" , "Dolt" , "Imbecile" , "nutter" , "Dunce" .)