Persistent, and flying out in case (9)
I believe the answer is:
tenacious
'persistent' is the definition.
(thesaurus)
'flying out in case' is the wordplay.
'flying' is an anagram indicator.
'out'+'in'+'case'='outincase'
'outincase' with letters rearranged gives 'TENACIOUS'.
'and' is the link.
(Other definitions for tenacious that I've seen before include "Dogged" , "Keeping a firm hold" , "Holding or sticking firmly" , "refusing to give up" , "Persistent in holding on" .)