Find out about struggle becoming more laborious (7)
I believe the answer is:
'more laborious' is the definition.
('heavy' can be a synonym of 'laborious')
'find out about struggle' is the wordplay.
'find out' becomes 'hear' ('hear' can be a synonym of 'find out').
'about' indicates putting letters inside.
'struggle' becomes 'vie' (I've seen this before).
'hear' placed around 'vie' is 'HEAVIER'.
'becoming' is the link.
(Other definitions for heavier that I've seen before include "Having greater weight" , "More difficult to lift" , "Less light" , "Weightier" , "with extra authority" .)