In being cunning, I'm seemingly servile (5)
I believe the answer is:
slimy
'seemingly servile' is the definition.
'slimy' can be an answer for 'servile' (thesaurus). I am not sure about the 'seemingly' bit.
'in being cunning i'm' is the wordplay.
'in' means one lot of letters goes inside another.
'being cunning' becomes 'sly' (synonyms).
'sly' enclosing 'im' is 'SLIMY'.
Can you help me to learn more?
(Other definitions for slimy that I've seen before include "Glutinous" , "Repulsively obsequious" , "toadying" , "Moist and slippery" , "Oleaginous" .)