Reportedly squeezes heavyweights (6)
I believe the answer is:
titans
'heavyweights' is the definition.
(I know this)
'reportedly squeezes' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'squeezes' becomes 'tightens'.
'tightens' sounds like 'TITANS'.
(Other definitions for titans that I've seen before include "Taints in giant men" , "Legendary giants with taints" , "Elder deities of Greek myth" , "Taints found in great men" , "Giant gods of Greek mythology" .)