Sons participating in healthy argument (6)
I believe the answer is:
hassle
'argument' is the definition.
(I've seen this before)
'sons participating in healthy' is the wordplay.
'sons' becomes 'ss' (s is abbreviation for son).
'participating in' means one lot of letters goes inside another.
'healthy' becomes 'hale' (similar in meaning).
'ss' inserted into 'hale' is 'HASSLE'.
(Other definitions for hassle that I've seen before include "Harass - grief" , "Wrangle" , "An informal quarrel or upset" , "Les has (anag) - a great deal of trouble" , "Lashes (anag)" .)