Lithe ibex fell badly (8)
I believe the answer is:
flexible
'lithe' is the definition.
(I've seen this before)
'ibex fell badly' is the wordplay.
'badly' indicates an anagram.
'ibex'+'fell'='ibexfell'
'ibexfell' is an anagram of 'FLEXIBLE'.
(Other definitions for flexible that I've seen before include "Pliant" , "Supple" , "Capable of bending without breaking" , "Giving" , "Not hard" .)