Dark suit shortened for disco? (9)
I believe the answer is:
nightclub
'disco?' is the definition.
(I've seen this before)
'dark suit shortened' is the wordplay.
'dark' becomes 'night' (it's dark at nighttime).
'suit' becomes 'clubs' (I've seen this in another clue).
'shortened' means to remove the last letter.
'clubs' with its last letter taken away is 'club'.
'night'+'club'='NIGHTCLUB'
'for' acts as a link.
(Other definitions for nightclub that I've seen before include "Where one might have room to swing" , "Hot spot" , "Place open late for entertainment, food and drink" , "cabaret" , "one of the high spots" .)