Heard team were breathing heavily (6)
I believe the answer is:
sighed
'were breathing heavily' is the definition.
(to sigh is to breathe heavily)
'heard team' is the wordplay.
'heard' shows a homophone (sound like).
'team' becomes 'side' (both can mean a sports team).
'side' is a homophone of 'SIGHED'.
(Other definitions for sighed that I've seen before include "Expressed impatience, longing" , "Breathed wearily" , "Took a deep audible breath" , "Moaned" , "Sounded weary" .)