I'm foxy about being obsequious! (5)
I believe the answer is:
slimy
'obsequious' is the definition.
(thesaurus)
'i'm foxy about' is the wordplay.
'foxy' becomes 'sly' (synonyms).
'about' indicates putting letters inside.
'im' inserted within 'sly' is 'SLIMY'.
'being' is the link.
(Other definitions for slimy that I've seen before include "Moist and slippery" , "Covered with slippery stuff, say mud" , "Glutinous" , "toadying" , "Oleaginous" .)