Stick found by National Trust supporter (8)
I believe the answer is:
adherent
'supporter' is the definition.
(I've seen this before)
'stick found by national trust' is the wordplay.
'stick' becomes 'adhere' (to adhere to something is to stick to it).
'found by' says to put letters next to each other.
'national trust' becomes 'nt'.
'adhere'+'nt'='ADHERENT'
(Other definitions for adherent that I've seen before include "Staunch follower" , "Freak" , "Supporter; sticking" , "Person supporting" , "Dedicated supporter" .)