Strong, quick to recover (9)
I believe the answer is:
resilient
I believe this is a double definition.
'strong' is the first definition.
(resilient can mean strong or tough)
'quick to recover' is the second definition.
(I've seen this in another clue)
(Other definitions for resilient that I've seen before include "Elastic" , "Rebounding from impact" , "Hardy" , "Flexible" , "able to withstand disappointment" .)