Prediction heard if warning players (7,8)
I believe the answer is:
weather forecast
'prediction' is the definition.
(weather forecast is a kind of prediction)
'heard if warning players' is the wordplay.
'heard' indicates a 'sounds like' (homophone) clue.
'if' becomes 'whether' (I've seen this before).
'warning' becomes 'fore' (I've seen this before).
'players' becomes 'cast' (I've seen this before).
'whether' sounds like 'weather'.
'weather'+'fore'+'cast'='WEATHER FORECAST'
(Other definitions for weather forecast that I've seen before include "prediction" , "Predicton" , "Met objective" , "item after news" .)