Son sickening at sea? (7)
I believe the answer is:
sailing
'at sea?' is the definition.
('sailing' can be a synonym of 'at sea')
'son sickening' is the wordplay.
I cannot quite understand how this works, but
'son' could be 's' (genealogical abbreviation for son) and 's' is found within the answer.
The remaining letters 'ailing' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sailing that I've seen before include "event" , "Eg, yachting" , "Water sport" , "Going by, eg, yacht" , "Marine sport" .)