Not enthused by abstract mural surrounding gardens (8)
I believe the answer is:
lukewarm
'not enthused' is the definition.
(as in a lukewarm reaction)
'abstract mural surrounding gardens' is the wordplay.
'abstract' indicates an anagram.
'surrounding' means one lot of letters goes inside another.
'gardens' becomes 'kew' (Kew Gardens in London).
'mural' with letters rearranged gives 'luarm'.
'luarm' placed around 'kew' is 'LUKEWARM'.
'by' acts as a link.
(Other definitions for lukewarm that I've seen before include "Somewhat cooler!" , "Not enthusiastic, neither hot nor cold" , "Tepid, or less than enthusiastic" , "Moist" , "Apathetic" .)