Much loved tree visited by leader of union (7)
I believe the answer is:
popular
'much loved' is the definition.
'popular' can be an answer for 'loved' (thesaurus). I'm not certain of the 'much' bit.
'tree visited by leader of union' is the wordplay.
'tree' becomes 'poplar tree' (poplar tree is a kind of tree).
'visited by' is an insertion indicator.
'leader of' indicates taking the first letters.
The initial letter of 'union' is 'u'.
'poplar' enclosing 'u' is 'POPULAR'.
Can you help me to learn more?
(Other definitions for popular that I've seen before include "Hot" , "Demotic" , "Fashionable" , "Well liked, generally admired" , "Non-technical" .)