It's more than cool from poster child dismissing hipster (4)
I believe the answer is:
cold
'it's more than cool' is the definition.
(I've seen this in another clue)
'from poster child dismissing hipster' is the wordplay.
'from' is an anagram indicator (from the letters).
'dismissing' indicates named letters should be taken away.
'poster'+'child'='posterchild'
'posterchild' with 'hipster' taken out is 'ocld'.
'ocld' with letters rearranged gives 'COLD'.
(Other definitions for cold that I've seen before include "Lacking affection" , "Stand-offish" , "Glacial" , "Chilly; minor ailment" , "Unemotional; wintry" .)