Hang about disco at first with sidekick (5)
I believe the answer is:
dally
'hang about' is the definition.
(thesaurus)
'disco at first with sidekick' is the wordplay.
'at first' says to take the initial letters.
'with' is a charade indicator (letters next to each other).
'sidekick' becomes 'ally' (a sidekick is a friend or ally).
The initial letter of 'disco' is 'd'.
'd'+'ally'='DALLY'
(Other definitions for dally that I've seen before include "Trifle" , "Dawdle - delay" , "Waste time" , "Move slowly" , "take time" .)