Group entering club unchallenged (5)
I believe the answer is:
bunch
'group' is the definition.
'entering club unchallenged' is the wordplay.
'entering' says the answer is hidden in the clue.
'BUNCH' is hidden in the letters of 'club unchallenged'.
(Other definitions for bunch that I've seen before include "Small group of flowers or people" , "Grouping of a number of similar things" , "Posy (of picked flowers)" , "Show silly fondness" , "Gang" .)