Spoils feature of Burns Night bringing in one vegetable (10)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Spoils feature of Burns Night bringing in one vegetable I (=one) in [MARS (=spoils, impairs) + PIPER (=feature of Burns Night, i.e. Scottish bagpiper)]; Maris Piper is a type of potato