Arctic boa, strangely gymnastic (9)
I believe the answer is:
acrobatic
'gymnastic' is the definition.
(synonyms)
'arctic boa strangely' is the wordplay.
'strangely' is an anagram indicator.
'arctic'+'boa'='arcticboa'
'arcticboa' anagrammed gives 'ACROBATIC'.
(Other definitions for acrobatic that I've seen before include "circus performer?" , "spectacularly agile" , "Involving physical agility" , "Gymnastically agile" , "Like a gymnastic entertainer" .)