More than one player is in new boots (7)
I believe the answer is:
oboists
'more than one player' is the definition.
(oboist is a kind of player)
'is in new boots' is the wordplay.
'in' indicates putting letters inside.
'new' indicates an anagram.
'boots' anagrammed gives 'obots'.
'is' put into 'obots' is 'OBOISTS'.
(Other definitions for oboists that I've seen before include "Woodwind players" , "10 across group" , "Musicians" .)