That is full of cold? (3)
I believe the answer is:
ice
'that is full of cold?' is the definition.
I can't judge whether this definition defines the answer.
'that is full of cold?' is the wordplay.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'full of' indicates putting letters inside.
'cold?' becomes 'c' (eg on taps).
'ie' placed around 'c' is 'ICE'.
(Other definitions for ice that I've seen before include "Precious stones" , "Cold stuff used in enticement" , "Glaciate" , "Cubes in a drink" , "Skating surface" .)