Cheese makes trio act badly (7)
I believe the answer is:
ricotta
'cheese' is the definition.
(ricotta is a type of cheese)
'trio act badly' is the wordplay.
'badly' is an anagram indicator (letters in the wrong order).
'trio'+'act'='trioact'
'trioact' anagrammed gives 'RICOTTA'.
'makes' is the link.
(Other definitions for ricotta that I've seen before include "cheese found" , "Italian 8 across" , "Sheep's milk cheese" , "may come from Italian press?" , "dairy produce" .)