Tap dancing cue in Grease (6)
I believe the answer is:
faucet
'tap' is the definition.
(term for a tap in US English)
'dancing cue in grease' is the wordplay.
'dancing' indicates an anagram.
'in' indicates putting letters inside.
'grease' becomes 'fat'.
'cue' with letters rearranged gives 'uce'.
'uce' placed into 'fat' is 'FAUCET'.
(Other definitions for faucet that I've seen before include "Pipe" , "Tap (US)" , "One may turn on this" , "North American tap" , "Spigot, tap" .)