The page Sean tore out shows a tree (5)
I believe the answer is:
aspen
'tree' is the definition.
(aspen is a kind of tree)
'the page sean tore out shows a' is the wordplay.
I cannot quite see how this works, but
'page' could be 'p' and 'p' is found in the answer.
an anagram of 'sean' is 'asen' which is located in the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for aspen that I've seen before include "Colorado ski resort - tree" , "winter resort" , "Growth" , "Tree that quivers" , "Colorado winter sports town" .)