Players seeing one's wearing new boots (7)
I believe the answer is:
oboists
'players' is the definition.
(oboist is a kind of player)
'one's wearing new boots' is the wordplay.
'one's' becomes 'is' (roman numeral).
'wearing' is an insertion indicator.
'new' is an anagram indicator.
'boots' with letters rearranged gives 'obots'.
'is' inserted inside 'obots' is 'OBOISTS'.
'seeing' is the link.
(Other definitions for oboists that I've seen before include "Musicians" , "10 across group" , "Woodwind players" .)