Cold girl in charge of major sporting event (7)
I believe the answer is:
classic
'major sporting event' is the definition.
(I've seen this before)
'cold girl in charge' is the wordplay.
'cold' becomes 'c' (eg on taps).
'girl' becomes 'lass' (lass can informally mean a girl).
'in charge' becomes 'ic' (abbreviation for 'in charge').
'c'+'lass'+'ic'='CLASSIC'
'of' acts as a link.
(Other definitions for classic that I've seen before include "Remarkably typical" , "Top-quality" , "Accepted as excellent" , "Work of established excellence (7)" , "Epsom Derby or St Leger Stakes, for example" .)