Deep red lips engaged in deception (7)
I believe the answer is:
crimson
'deep red' is the definition.
(synonyms)
'lips engaged in deception' is the wordplay.
'lips' becomes 'rims' ('rim' can be a synonym of 'lip').
'engaged in' indicates putting letters inside.
'deception' becomes 'con' (I've seen this before).
'rims' put inside 'con' is 'CRIMSON'.
(Other definitions for crimson that I've seen before include "Deep red colour" , "Become red-faced" , "Flushed" , "Colour of deep blushing?" , "Rich deep red" .)