Gets colder (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
cools
'gets colder' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for cools that I've seen before include "Loses heat" , "Becomes less ardent" , "Chills" , "Gets colder" .)