See you grabbing tail of sleek otter (5)
I believe the answer is:
tarka
'otter' is the definition.
(I've seen this before)
'see you grabbing tail of sleek' is the wordplay.
'see you' becomes 'ta-ra' (both can mean goodbye).
'grabbing' means one lot of letters goes inside another.
'tail of' indicates one should take the final letters.
The last letter of 'sleek' is 'k'.
'tara' placed around 'k' is 'TARKA'.
(Other definitions for tarka that I've seen before include "One after fish booked" , "Literary otter" , "Henry Williamson's otter" , "Swimmer in story" , "Fictional otter" .)