Mention some illicit encounter (4)
I believe the answer is:
cite
'mention' is the definition.
(to cite is to mention or quote)
'some illicit encounter' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'CITE' can be found hidden inside 'illicit encounter'.
(Other definitions for cite that I've seen before include "Quote (eg, a book)" , "Summon - quote" , "Quote (an author)" , "Quote as authority" , "Mention as example or quote" .)