Very hot yet was composed (6)
I believe the answer is:
sweaty
'very hot' is the definition.
(you might sweat when you're hot)
'yet was composed' is the wordplay.
'composed' indicates anagramming the letters.
'yet'+'was'='yetwas'
'yetwas' is an anagram of 'SWEATY'.
(Other definitions for sweaty that I've seen before include "Showing effects of fever" , "Damp with perspiration" , "affected by the heat" , "Hot and perspiring" , "like some athletes in competition?" .)