Shout with pain, with heart maybe leading to caution in game (6,4)
I believe the answer is:
yellow card
'caution in game' is the definition.
'shout with pain with heart maybe leading' is the wordplay.
'shout' becomes 'yell' (yelling is a kind of shouting).
'with' says to put letters next to each other.
'pain with' becomes 'ow' (I can't justify this - if you can you should believe this answer much more).
'heart maybe' becomes 'card'.
'leading' is a charade indicator (letters next to each other).
'yell'+'ow'+'card'='YELLOW CARD'
'to' acts as a link.
(Other definitions for yellow card that I've seen before include "Warning leading to temporary dismissal" , "Warning to footballer" , "Footballer's caution" , "Warning to footballers" , "With which a referee cautions player" .)