Mischief-maker speaks deceitfully and makes insinuations (7)
I believe the answer is:
implies
'makes insinuations' is the definition.
(to imply is to insinuate)
'mischief-maker speaks deceitfully' is the wordplay.
'mischief maker' becomes 'imp' (I've seen this in other clues).
'speaks deceitfully' becomes 'lies' (I can't justify this - if you can you should give a lot more credence to this answer).
'imp'+'lies'='IMPLIES'
'and' is the link.
Can you help me to learn more?
(Other definitions for implies that I've seen before include "States indirectly" , "Suggests or hints at meaning" , "Insinuates" .)