Alienate set struggling with diversity (8)
I believe the answer is:
estrange
'alienate' is the definition.
(synonyms)
'set struggling with diversity' is the wordplay.
'struggling' indicates anagramming the letters (the letters struggle or wriggle into a new form).
'with' means one lot of letters go next to another.
'diversity' becomes 'range' (I've seen this in another clue).
'set' with letters rearranged gives 'est'.
'est'+'range'='ESTRANGE'
(Other definitions for estrange that I've seen before include "Forfeit friendship of, make hostile" , "As Regent (anag.)" , "Reagents (anag.)" , "Ten gears (anag.)" , "may break up" .)