Worries about son's light touch (6)
I believe the answer is:
caress
'light touch' is the definition.
(thesaurus)
'worries about son's' is the wordplay.
'worries' becomes 'cares' (I've seen this before).
'about' indicates putting letters inside.
'cares' enclosing 's' is 'CARESS'.
(Other definitions for caress that I've seen before include "Stroke lightly in a loving manner" , "Stroke fondly" , "show of affection" , "Touch with affection" , "Scares with loving stroke" .)