First two characters to leave Belgian town (5)
I believe the answer is:
elgin
'town' is the definition.
(I've seen this before)
'first two characters to leave belgian' is the wordplay.
'first two characters' becomes 'ab' (A and B are the first letters of the alphabet).
'to leave' indicates named letters should be taken away.
'belgian' with 'ab' removed is 'ELGIN'.
(Other definitions for elgin that I've seen before include "Marble-gathering earl" , "Parthenon marbles remover" , "Moray town, Earldom" , "Sculpture collector" , "Scots town; - marbles" .)