Move around the Tube, essentially underground in America (6)
I believe the answer is:
subway
'underground in america' is the definition.
'subway' can be an answer for 'underground' (synonyms). I'm not sure about the 'in america' bit.
'move around the tube essentially' is the wordplay.
'move' becomes 'sway' (sway is a kind of move).
'around' is an insertion indicator.
'essentially' says to take the centre.
The centre of 'tube' is 'ub'.
'sway' placed around 'ub' is 'SUBWAY'.
Can you help me to learn more?
(Other definitions for subway that I've seen before include "New York railway" , "pedestrian passage?" , "NY underground" , "New York underground" , "Underground passage" .)