Snake catches Native American airing out before it can climb walls (8,7)
I believe the answer is:
virginia creeper
'it can climb walls' is the definition.
'snake catches native american airing out before' is the wordplay.
'snake' becomes 'viper' (viper is a kind of snake**).
'catches' means one lot of letters goes inside another.
'native american' becomes 'cree' (an indigenous people of North America).
'out' is an anagram indicator (out can mean wrong or inaccurate).
'before' says to put letters next to each other.
'airing' anagrammed gives 'rginia'.
'cree' after 'rginia' is 'rginiacree'.
'viper' going around 'rginiacree' is 'VIRGINIA CREEPER'.
(Other definitions for virginia creeper that I've seen before include "plant" , "going up the wall!" , "Climber" .)