Animal suffering with external limb trouble (9)
I believe the answer is:
armadillo
'animal' is the definition.
(armadillo is a kind of animal)
'suffering with external limb trouble' is the wordplay.
'suffering' becomes 'ill' (suffering with illness).
'with external' is an insertion indicator.
'limb' becomes 'arm' (arm is a kind of limb).
'trouble' becomes 'ado' (both can mean bother or commotion).
'arm'+'ado'='armado'
'ill' inserted inside 'armado' is 'ARMADILLO'.
(Other definitions for armadillo that I've seen before include "Mammal with protective plates" , "Toothless Native American" , "Bony-plated mammal" , "American insect-eater" , "Insect-eating mammal" .)