Sporting giant — taking care, serving (9)
I believe the answer is:
attending
'serving' is the definition.
('attend' can be a synonym of 'serve')
'sporting giant taking care' is the wordplay.
'sporting' is an anagram indicator.
'taking' means one lot of letters goes inside another.
'care' becomes 'tend' (I've seen this in other clues).
'giant' with letters rearranged gives 'ating'.
'ating' enclosing 'tend' is 'ATTENDING'.
(Other definitions for attending that I've seen before include "Paying attention" , "Listening or being present at" , "Being present at (function/event)" .)