Trained guardians removing grid where it gets quite hot (5)
I believe the answer is:
sauna
'where it gets quite hot' is the definition.
(saunas get hot)
'trained guardians removing grid' is the wordplay.
'trained' is an anagram indicator (to train can mean to grow something into a shape).
'removing' is a deletion indicator.
'guardians' with 'grid' taken away is 'uaans'.
'uaans' with letters rearranged gives 'SAUNA'.
(Other definitions for sauna that I've seen before include "A Scandinavian steam bath" , "Form of steam bath" , "Steam-heated room" , "Very hot room for cleansing, of Finnish origin" , "Where one is sweaty" .)