Hot dish, then cold, very cold (6)
I believe the answer is:
baltic
'very cold' is the definition.
(baltic can informally mean very cold)
'hot dish then cold' is the wordplay.
'hot dish' becomes 'balti' (I've seen this before).
'then' is a charade indicator (letters next to each other).
'cold' becomes 'c' (eg on taps).
'balti'+'c'='BALTIC'
(Other definitions for baltic that I've seen before include "North European sea" , "cold waters" , "Almost land-locked sea of NE Europe" , "Cab lit up the sea" , "Sea of northern Europe" .)