Warning gong in Central Park (5)
I believe the answer is:
amber
'warning' is the definition.
(amber traffic light)
'gong in central park' is the wordplay.
'gong' becomes 'MBE' (Member of the Order of the British Empire).
'in' is an insertion indicator.
'central' says to take the centre.
The middle of 'park' is 'ar'.
'mbe' placed into 'ar' is 'AMBER'.
(Other definitions for amber that I've seen before include "first light" , "Cautionary colour" , "Fossil resin - bream (anag)" , "Yellowish translucent fossil resin" , "Road warning" .)