Lowly worker grabs knight before a line dance (5)
I believe the answer is:
conga
'line dance' is the definition.
(I've seen this before)
'lowly worker grabs knight before a' is the wordplay.
'lowly worker' becomes 'cog' (just a cog in the machine).
'grabs' is an insertion indicator.
'knight' becomes 'N' (chess abbreviation).
'before' says to put letters next to each other.
'cog' going around 'n' is 'cong'.
'cong'+'a'='CONGA'
(Other definitions for conga that I've seen before include "Party dance" , "Latin American "follow-my-leader" dance" , "Dance performed in line" , "Long-line dance" , "Lined-up dance" .)