Below, pass is shady (9)
I believe the answer is:
underhand
'shady' is the definition.
(thesaurus)
'below pass' is the wordplay.
'below' becomes 'under' ('under' can be a synonym of 'below').
'pass' becomes 'hand' ('hand' can be a synonym of 'pass'**).
'under'+'hand'='UNDERHAND'
'is' is the link.
(Other definitions for underhand that I've seen before include "might be deceptive" , "Surreptitiously, sounds like a lower employee" , "way of delivering service." , "Surreptitious" , "Unsporting" .)