Ref endlessly took risks over winning goal (7)
I believe the answer is:
decider
'winning goal' is the definition.
'decider' can be an answer for 'goal' (I have seen 'Ultimate goal' mean 'decider' so perhaps 'goal' could also mean 'decider'). I'm not sure about the 'winning' bit.
'ref endlessly took risks over' is the wordplay.
'endlessly' means to remove the last letter.
'took risks' becomes 'diced' (to dice is to gamble or take risks).
'over' says the letters should be written in reverse.
'ref' with its final letter taken off is 're'.
're'+'diced'='rediced'
'rediced' back-to-front is 'DECIDER'.
Can you help me to learn more?
(Other definitions for decider that I've seen before include "Clinching game" , "It settles the matter" , "The game that determines the series winner" , "Extra period of play to settle a draw" , "Ultimate goal" .)