Cases include new garden features (5)
I believe the answer is:
ponds
'garden features' is the definition.
Although both the answer and definition are plural nouns, I can't understand how they can define each other.
'cases include new' is the wordplay.
'cases' becomes 'pods' (pod is a kind of case).
'include' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'pods' enclosing 'n' is 'PONDS'.
Can you help me to learn more?
(Other definitions for ponds that I've seen before include "Small artificial lakes" , "Pools" .)