Tools needed for a quarter of the deck (6)
I believe the answer is:
spades
This clue is a double definition.
'tools' is the first definition.
(spade is a kind of tool)
'for a quarter of the deck' is the second definition.
(I've seen this in another clue)
'needed' acts as a link.
(Other definitions for spades that I've seen before include "Implements for a suit" , "Digging tools and card suit" , "Black suit" , "Garden tools and card suit" , "Passed around with diggers" .)