Cold day: like to get up? (6)
I believe the answer is:
frigid
'cold' is the definition.
('frigid' can be similar in meaning to 'cold')
'day like to get up?' is the wordplay.
'day' becomes 'fri'.
'like' becomes 'dig' (I've seen this in other clues).
'to get up?' is a reversal indicator (I've seen 'got up' mean this).
'dig' backwards is 'gid'.
'fri'+'gid'='FRIGID'
(Other definitions for frigid that I've seen before include "Sexually unresponsive" , "Cold and unresponsive" , "Very cold; formal in behaviour" , "Passionless, unresponsive" , "Stiff - cold - formal" .)