Smoothed with heat (6)
I believe the answer is:
ironed
'smoothed with heat' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ironed that I've seen before include "Given a press" , "Smoothed the cloth with heat" , "Smoothed with domestic device" , "Had an evening out" , "Smoothed cloth with flatbased implement" .)