Turn tail as troubled student of life (10)
I believe the answer is:
naturalist
'student of life' is the definition.
'turn tail as troubled' is the wordplay.
'troubled' indicates anagramming the letters.
'turn'+'tail'+'as'='turntailas'
'turntailas' anagrammed gives 'NATURALIST'.
(Other definitions for naturalist that I've seen before include "Darwin?" , "Zoologist" , "one's studying in the wild" , "Zoology expert possibly" , "One who studies animals and plants" .)