At 170K miles your clutch could be telling you it is on it’s last legs. Have you tested it for slippage? Put it in 5th gear, give it some gas and let out the clutch. The motor should stall and stop completely. If it keeps running your clutch is slipping and the smell is due to the heat from friction due to the slipping.
Since the OP mention “clutch” I’m assuming this is a manual transmission car. If in fact it has an automatic transmission - disregard my reply.