Reflection of sound around large island results in slurring of words (7)
I believe the answer is:
elision
'slurring of words' is the definition.
(the merging of sounds together)
'reflection of sound around large island' is the wordplay.
'reflection of' says the letters should be written in reverse (I've seen 'reflection' mean this).
'sound' becomes 'noise' (noising is a kind of sounding).
'around' means one lot of letters goes inside another.
'large' becomes 'l'.
'island' becomes 'i'.
'noise' reversed gives 'esion'.
'l'+'i'='li'
'esion' going around 'li' is 'ELISION'.
'results in' is the link.
(Other definitions for elision that I've seen before include "Omission (from a book, etc)" , "Omission of a sound in speech" , "Omission (of a syllable)" , "Dropping a letter" , "Omission of syllables in speech" .)