It's boos, regrettably, for woodwind players (7)
I believe the answer is:
oboists
'woodwind players' is the definition.
(I've seen this before)
'it's boos regrettably' is the wordplay.
'regrettably' is an anagram indicator.
'its'+'boos'='itsboos'
'itsboos' with letters rearranged gives 'OBOISTS'.
'for' acts as a link.
(Other definitions for oboists that I've seen before include "Woodwind players" , "10 across group" , "Musicians" .)