Energy of southern squad (5)
I believe the answer is:
steam
'energy' is the definition.
(I've seen this before)
'southern squad' is the wordplay.
'southern' becomes 's' (abbreviation).
'squad' becomes 'team' (synonyms).
's'+'team'='STEAM'
'of' acts as a link.
(Other definitions for steam that I've seen before include "Vaporous exhalation" , "Cook" , "Water at boiling temperature diffused in the atmosphere" , "Water-vapour" , "Gas formed by vaporizing water at 100?C" .)