Involve mischievous child with tall story about pet (9)
I believe the answer is:
implicate
'involve' is the definition.
(thesaurus)
'mischievous child with tall story about pet' is the wordplay.
'mischievous child' becomes 'imp' (I've seen this before).
'with' means one lot of letters go next to another.
'tall story' becomes 'lie'.
'about' means one lot of letters goes inside another.
'pet' becomes 'cat' (I have seen 'Common pet ' mean 'cat' so perhaps 'pet' could also mean 'cat'**).
'lie' going around 'cat' is 'licate'.
'imp'+'licate'='IMPLICATE'
(Other definitions for implicate that I've seen before include "Suggest someone else is involved in your crime" , "Involve in a crime, give evidence accordingly" , "Point finger at criminal" , "Suggest someone is involved or took part in a crime" , "Involve in a crime, ensnare" .)