Note boxer's twitching, with both feet on the ground? (9)
I believe the answer is:
realistic
'with both feet on the ground?' is the definition.
(someone with both feet on the ground is a realist)
'note boxer's twitching' is the wordplay.
'note' becomes 're'.
'boxer's' becomes 'alis' (Muhammad Ali).
'twitching' becomes 'tic' (tic is a kind of twitching).
're'+'alis'+'tic'='REALISTIC'
(Other definitions for realistic that I've seen before include "accurate picture" , "Practicable" , "Facing facts, as it is clear" , "It is clear, being practical and sensible" , "Level-headed" .)