Instruments for blowers regularly seen (5)
I believe the answer is:
oboes
'instruments' is the definition.
(oboe is a kind of instrument)
'for blowers regularly seen' is the wordplay.
'regularly seen' means one should take alternating letters.
'for'+'blowers'='forblowers'
The alternate letters of 'forblowers' are 'OBOES'.
(Other definitions for oboes that I've seen before include "Wind instruments" , "Woodwind instruments" , "Parts of orchestra" , "They're instrumental" , "members of orchestra" .)