Foxtrot with nimble steps (6)
I believe the answer is:
flight
'steps' is the definition.
(I've seen this before)
'foxtrot with nimble' is the wordplay.
'foxtrot' becomes 'f' (phonetic alphabet: alpha, bravo, charlie etc.).
'with' says to put letters next to each other.
'nimble' becomes 'light' (synonyms).
'f'+'light'='FLIGHT'
(Other definitions for flight that I've seen before include "Journey by air" , "the vanquished may take?" , "Trip by air" , "A series of stairs" , "The feathers on a dart or arrow" .)