Something cold seen during Antarctic expedition (3)
I believe the answer is:
ice
'something cold' is the definition.
'during antarctic expedition' is the wordplay.
'during' indicates a hidden word.
'ICE' is hidden in the letters of 'antarctic expedition'.
'seen' is the link.
(Other definitions for ice that I've seen before include "Block" , "Skating surface" , "Diamonds, colloquially" , "Diamonds (informal)" , "Frozen liquid" .)