Amin turned to ice, almost? That's daft! (7)
'daft' is the definition.
(I've seen this before)
'amin turned to ice almost?' is the wordplay.
'amin' becomes 'idi' (I've seen this in other clues).
'turned' is a reversal indicator.
'almost?' means to remove the last letter (most of the word but not all of it).
'to' reversed gives 'ot'.
'ice' with its final letter taken off is 'ic'.
'that's' acts as a link.
(Other definitions for idiotic that I've seen before include "Daft", "Altogether nonsensical", "Inviting ridicule", "without intelligence", "Fatuous".)