Musician in bad temper following tense game (9)
I believe the answer is:
trumpeter
'musician' is the definition.
(I know that trumpeter is a type of musician)
'bad temper following tense game' is the wordplay.
'bad' indicates an anagram.
'following' means one lot of letters go next to another.
'tense' becomes 't' (abbreviation used in many dictionaries).
'game' becomes 'RU' (rugby union).
'temper' with letters rearranged gives 'mpeter'.
't'+'ru'='tru'
'mpeter' after 'tru' is 'TRUMPETER'.
'in' is the link.
(Other definitions for trumpeter that I've seen before include "[SOMETHING FISHY]" , "It's the valve operator" , "one of a band" , "Boastful" , "Instrumentalist - type of swan" .)