Slippery, perhaps, and grey as can be (6)
I believe the answer is:
greasy
'slippery' is the definition.
('greasy' can be similar in meaning to 'slippery')
'grey as can be' is the wordplay.
'can be' indicates an anagram.
'grey'+'as'='greyas'
'greyas' with letters rearranged gives 'GREASY'.
'perhaps and' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for greasy that I've seen before include "Covered in oil" , "well-lubricated" , "Thickly oleaginous" , "Unctuous or ingratiating" , "Like the pole that is hard to climb" .)