Turn southwest with lively heart (6)
I believe the answer is:
swivel
'turn' is the definition.
(swiveling is a kind of turning)
'southwest with lively heart' is the wordplay.
'southwest' becomes 'sw' (synonyms).
'with' is a charade indicator (letters next to each other).
'heart' says to take the centre.
The central letters of 'lively' are 'ivel'.
'sw'+'ivel'='SWIVEL'
(Other definitions for swivel that I've seen before include "Kind of chair with seat that turns horizontally" , "Swing on a pivot" , "Turn on the spot" , "Revolving coupling" , "something pivotal" .)