Instrumentalist going round station trapping serpent (3,5)
I believe the answer is:
pit viper
'serpent' is the definition.
(pit viper is a kind of serpent)
'instrumentalist going round station trapping' is the wordplay.
'instrumentalist' becomes 'piper' (piper is a kind of instrumentalist).
'going round' means one lot of letters goes inside another (some letters go around others).
'station trapping' becomes 'tvi' (I can't explain this - if you can you should give a lot more credence to this answer).
'piper' enclosing 'tvi' is 'PIT-VIPER'.
Can you help me to learn more?
(Other definitions for pit viper that I've seen before include "Reptile" , "One may rattle" , "I may employ venom" , "Rattlesnake" , "Venomous snake" .)