Slow learner hit out with grace (9)
I believe the answer is:
lethargic
'slow' is the definition.
(I've seen this before)
'learner hit out with grace' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'out with' indicates an anagram (out can mean wrong or inaccurate).
'hit' with its letters mixed up with 'grace' makes 'ethargic'.
'l'+'ethargic'='LETHARGIC'
(Other definitions for lethargic that I've seen before include "Unenergetic" , "languid" , "without energy" , "The garlic (anag.)" , "Lacking energy/enthusiasm" .)