Hot swimmer is accommodating at any time (8)
I believe the answer is:
feverish
'hot' is the definition.
(thesaurus)
'swimmer is accommodating at any time' is the wordplay.
'swimmer' becomes 'fish' (fish is a kind of aquatic vertebrate).
'is accommodating' is an insertion indicator.
'at any time' becomes 'ever' (synonyms).
'fish' enclosing 'ever' is 'FEVERISH'.
(Other definitions for feverish that I've seen before include "Suffering from a high temperature" , "hectic" , "restless state" , "Febrile" , "highly charged" .)