They get heated when there's a toss up! (5)
I believe the answer is:
oasts
'they get heated' is the definition.
The definition suggests an adverb but the answer is not.
'there's a toss up' is the wordplay.
'there's' is a charade indicator (letters next to each other).
'up' indicates anagramming the letters.
'a' next to 'toss' is 'atoss'.
'atoss' anagrammed gives 'OASTS'.
'when' acts as a link.
Can you help me to learn more?
(Other definitions for oasts that I've seen before include "Houses" , "Malt dryers" , "Kilns for drying hops" .)