Scrap outside trendy nightclub (5)
I believe the answer is:
joint
'nightclub' is the definition.
(joint can mean a club or bar)
'scrap outside trendy' is the wordplay.
'scrap' becomes 'jot' (I've seen this before).
'outside' means one lot of letters goes inside another (some letters go outside others).
'trendy' becomes 'in' ('in' can mean fashionable).
'jot' going around 'in' is 'JOINT'.
(Other definitions for joint that I've seen before include "Bone junction" , "Structure by which bones are fitted together" , "Combined" , "eg Knee" , "Flexible link" .)