Difficult to shake off, which is awkward (6)
I believe the answer is:
sticky
This could be a double definition.
'difficult to shake off which' is the first definition.
'sticky' can be an answer for 'difficult' (I've seen this in another clue). I'm unsure of the rest of the definition.
'awkward' is the second definition.
(synonyms)
'is' is the link.
Can you help me to learn more?
(Other definitions for sticky that I've seen before include "Glutinous, gooey" , "Awkward - viscous" , "Awkward - muggy" , "Warm and humid" , "sultry?" .)