Second favourite reversed dance movement (4)
I believe the answer is:
step
'dance movement' is the definition.
(I've seen this before)
'second favourite reversed' is the wordplay.
'second' becomes 's' (common abbreviation).
'favourite' becomes 'pet' ('pet' can be a synonym of 'favourite').
'reversed' says the letters should be written in reverse.
'pet' in reverse letter order is 'tep'.
's'+'tep'='STEP'
(Other definitions for step that I've seen before include "Put foot on a pest" , "Pace; foothold" , "A pace for pets" , "Abrupt change; pace" , "Place foot on as with a pest" .)