Tree regularly spreads in garden close to fence (8)
I believe the answer is:
pedigree
'tree' is the definition.
(thesaurus)
'regularly spreads in garden close to fence' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'close to' says to take the final letters (the close/ending of).
The final letter of 'fence' is 'e'.
'spreads'+'in'+'garden'='spreadsingarden'
The alternating letters of 'spreadsingarden' are 'pedigre'.
'pedigre'+'e'='PEDIGREE'
(Other definitions for pedigree that I've seen before include "Record of descent" , "Ancestry of a purebred animal" , "Line of ancestry, particularly a distinguished one" , "(Distinguished) lineage" , "Line of descent, family tree" .)