Smart bear nicking king’s desktop device (8)
I believe the answer is:
inkstand
'desktop device' is the definition.
(device once found on desks)
'smart bear nicking king's' is the wordplay.
'smart' becomes 'in' (as in fashionable).
'bear' becomes 'stand' (synonyms).
'nicking' indicates putting letters inside (I've seen this in other clues).
'king' becomes 'K' (abbreviation for king in chess).
'in'+'stand'='instand'
'instand' placed around 'k' is 'INKSTAND'.
(Other definitions for inkstand that I've seen before include "Holder for writing materials" , "Desktop item" , "Kind Stan (anag.)" , "place for quills etc" , "old-fashioned writer may need this" .)