Diamonds I spread out for show (7)
I believe the answer is:
display
'show' is the definition.
(display is a kind of show)
'diamonds i spread out' is the wordplay.
'diamonds' becomes 'd' (abbreviation in bridge say).
'spread out' becomes 'splay' ('splay' can be a synonym of 'spread out').
'd'+'i'+'splay'='DISPLAY'
'for' acts as a link.
(Other definitions for display that I've seen before include "Put on show" , "Exhibit, show" , "Demonstrate, show" , "Show to the public" , "Reveal" .)