Fool taking heather to be small tree (7)
I believe the answer is:
sapling
'small tree' is the definition.
'sapling' can be an answer for 'tree' (I have seen 'Young tree' mean 'sapling' so perhaps 'tree' could also mean 'sapling'). I am unsure of the 'small' bit.
'fool taking heather' is the wordplay.
'fool' becomes 'sap' (synonyms).
'taking' says to put letters next to each other.
'heather' becomes 'ling' (synonyms).
'sap'+'ling'='SAPLING'
'to be' acts as a link.
Can you help me to learn more?
(Other definitions for sapling that I've seen before include "Little tree" , "Young slender tree" , "small bit of wood" , "Poetic youth" , "Lapsing into a young tree" .)