Tantrum, looking back, depressed second clarinettist as well as composer (5)
I believe the answer is:
elgar
'composer' is the definition.
(Edward Elgar)
'tantrum looking back depressed second clarinettist as well' is the wordplay.
I cannot really understand how this works, but
'second clarinettist' could be 'l' (2nd letter of 'clarinettist') and 'l' is found in the answer.
'as' could be 'eg' ('as' and 'e.g.' can both mean for example) and 'eg' is located in the leftover letters.
The remaining letters 'ar' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'as' is the link.
Can you help me to learn more?
(Other definitions for elgar that I've seen before include "[NIMROD] 's creator" , "British composer, d. 1934" , "Enigma Variations composer" , "Enigma Vars. composer" , "Score-person" .)