Weighty report about part of wheel (4)
I believe the answer is:
tyre
'part of wheel' is the definition.
(I know that tyre is part of wheel)
'weighty report about' is the wordplay.
'about' indicates the answer is hidden within the clue (the clue goes around or about the answer).
'TYRE' can be found hidden inside 'weighty report'.
(Other definitions for tyre that I've seen before include "Rubber wheel-cover" , "Rubber tube on a wheel" , "Rubber covering on a wheel" , "Wheel cover, may be tubeless" , "Travelling band" .)