Green’s Dictionary of Slang

(drugs) the effect gained by consuming a given drug.

2005		Urban Dict. 2 June 🌐 dunt The ‘hit’ obtained from the ingestion of a drug. I downed a bottle of tonic wine on top of a half-glass of Calpol for a cheap dunt.
2020		G. Armstrong Young Team 138: A pull two eckies oot ma pocket [...] tan half ma WKD tae wash them back, double duntin.