Glide or dash off, not finishing (4)
I believe the answer is:
skim
'glide' is the definition.
(skimming is a kind of gliding)
'dash off not finishing' is the wordplay.
'dash off' becomes 'skimp' (both can mean to do something carelessly).
'not finishing' means to remove the last letter.
'skimp' with its last letter taken off is 'SKIM'.
'or' acts as a link.
(Other definitions for skim that I've seen before include "Brush over" , "copy information illegally" , "avoid paying income tax" , "Glide smoothly over" , "Glance over" .)