Mockery that's terribly cruel about Amin (8)
I believe the answer is:
ridicule
'mockery' is the definition.
(I know that mockery can be written as ridicule)
'terribly cruel about amin' is the wordplay.
'terribly' indicates an anagram.
'about' is an insertion indicator.
'amin' becomes 'idi' (I've seen this in other clues).
'cruel' with letters rearranged gives 'rcule'.
'rcule' placed around 'idi' is 'RIDICULE'.
'that's' is the link.
(Other definitions for ridicule that I've seen before include "Poke fun at" , "Laugh at or deride" , "Meek" , "Pour scorn on" , "Lampoon" .)