Tension of a new team yet to play (7)
I believe the answer is:
anxiety
'tension' is the definition.
(thesaurus)
'a new team yet to play' is the wordplay.
'a new' becomes 'an' (I've seen this in other clues).
'team' becomes 'xi' (eleven, a football team).
'to play' indicates anagramming the letters.
'yet' is an anagram of 'ety'.
'an'+'xi'+'ety'='ANXIETY'
'of' acts as a link.
(Other definitions for anxiety that I've seen before include "Worry, state of fretfulness" , "Disquiet" , "Worry, concern" , "Nervousness" , "Great unease" .)