A new team’s entry often causes worry (7)
I believe the answer is:
anxiety
'worry' is the definition.
(I've seen this before)
'a new team's entry often' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is present in the answer.
'team' could be 'xi' (a football team, from Roman numerals for 11) and 'xi' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'causes' is the link.
Can you help me to learn more?
(Other definitions for anxiety that I've seen before include "Worried state" , "Worry, concern" , "Worry, state of fretfulness" , "Worry, unease" , "Disquiet" .)