Sit back in a tree awkwardly and study (8)
I believe the answer is:
treatise
'study' is the definition.
(I've seen this before)
'sit back in a tree awkwardly' is the wordplay.
'back' says the letters should be written in reverse.
'in' indicates putting letters inside.
'awkwardly' is an anagram indicator.
'sit' backwards is 'tis'.
'a'+'tree'='atree'
'atree' anagrammed gives 'treae'.
'tis' inserted within 'treae' is 'TREATISE'.
'and' acts as a link.
(Other definitions for treatise that I've seen before include "Long, detailed essay" , "Systematically-written formal piece" , "Written study" , "Iterates in essay" , "Learned work formally dealing with a subject" .)