Twig at intervals swimming coach admits being confused (7)
I believe the answer is:
chaotic
'being confused' is the definition.
(confused can mean chaotic or muddled)
'twig at intervals swimming coach admits' is the wordplay.
'at intervals' means one should take alternating letters (letters are taken at regular intervals).
'swimming' is an anagram indicator.
'admits' indicates putting letters inside.
The alternating letters of 'twig' are 'ti'.
'coach' anagrammed gives 'chaoc'.
'ti' inserted inside 'chaoc' is 'CHAOTIC'.
(Other definitions for chaotic that I've seen before include "mess" , "In total disorder" , "Disorderly, shambolic" , "Confused and disorderly" , "totally out of order?" .)