Perhaps ring me about large mischief-maker (7)
I believe the answer is:
gremlin
'mischief-maker' is the definition.
(magical creature)
'perhaps ring me about large' is the wordplay.
'perhaps' indicates an anagram.
'about' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'ring'+'me'='ringme'
'ringme' is an anagram of 'gremin'.
'gremin' going around 'l' is 'GREMLIN'.
(Other definitions for gremlin that I've seen before include "Unexplained technical problem or fault" , "One sabotages" , "Troublemaking goblin" , "Technical bug" , "Mischievous goblin" .)