In winter I'm expecting frost (4)
I believe the answer is:
rime
'frost' is the definition.
(rime is frost formed by freezing water vapour)
'in winter i'm expecting' is the wordplay.
'in' indicates a hidden word.
'RIME' can be found hidden inside 'winter im expecting'.
(Other definitions for rime that I've seen before include "''The ... of the Ancient Mariner'' (Coleridge)" , "Ancient Mariner produced?" , "Frost left after freezing fog, or frozen dew" , "Hoar frost" , "Kind of frost in mire" .)