Small group of players with energy (5)
I believe the answer is:
steam
'energy' is the definition.
(I've seen this before)
'small group of players' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'group of players' becomes 'team' (I've seen this before).
's'+'team'='STEAM'
'with' is the link.
(Other definitions for steam that I've seen before include "enthusiasm" , "Source of energy" , "Form of water" , "Type of power" , "Old-fashioned power" .)