Misbehaving oldsters liked to be dolled up (7,2,4)
I believe the answer is:
dressed to kill
'be dolled up' is the definition.
('dressed to kill' can be a synonym of 'dolled up')
'misbehaving oldsters liked' is the wordplay.
'misbehaving' is an anagram indicator.
'oldsters'+'liked'='oldstersliked'
'oldstersliked' is an anagram of 'DRESSED TO KILL'.
'to' is the link.
(Other definitions for dressed to kill that I've seen before include "All dolled up -- liked oldsters (anag)" , "in fine threads" , "Looking really attractive" , "Done up to the nines" , "smartly attired" .)