Log found in frozen terrain (5)
I believe the answer is:
enter
'log' is the definition.
(as in logging or entering information to a record)
'in frozen terrain' is the wordplay.
'in' indicates a hidden word.
'ENTER' is hidden in the letters of 'frozen terrain'.
'found' acts as a link.
(Other definitions for enter that I've seen before include "Set foot in" , "Come or go in" , "Go/come in" , "Make a record of" , "Join (for the first time)" .)