Affectionate gesture worries son (6)
I believe the answer is:
caress
'affectionate gesture' is the definition.
(I've seen this in another clue)
'worries son' is the wordplay.
'worries' becomes 'cares' (I've seen this in another clue).
'son' becomes 's' (genealogical abbreviation for son).
'cares'+'s'='CARESS'
(Other definitions for caress that I've seen before include "Stoke affectionately" , "Affectionate stroke" , "Gentle loving touch" , "Stroke, fondle" , "Stroke lightly in a loving manner" .)