Be rude to commanding officer in club (5)
I believe the answer is:
disco
'club' is the definition.
(night club)
'be rude to commanding officer' is the wordplay.
'be rude to' becomes 'dis' (I've seen this in another clue).
'commanding officer' becomes 'co'.
'dis'+'co'='DISCO'
'in' acts as a link.
(Other definitions for disco that I've seen before include "1970s' musical genre" , "Nightclub with recorded music, in short" , "Dance hall - music by Donna Summer and the Bee Gees, say" , "Place to dance to recorded music, in short" , "Club or party with dancing" .)