A team failing -- you are caught being unprofessional (7)
I believe the answer is:
amateur
'unprofessional' is the definition.
(synonyms)
'a team failing you are caught' is the wordplay.
'failing' is an anagram indicator.
'you' becomes 'u' (commonly used in online communication).
'caught' shows a homophone (sound like) (heard).
'are' is a homophone of 'r'.
'team' is an anagram of 'mate'.
'a'+'mate'+'u'+'r'='AMATEUR'
'being' acts as a link.
(Other definitions for amateur that I've seen before include "Ham" , "Inexpert" , "Layman" , "inept player" , "Person who does something as a pastime rather than a profession" .)