It could veer to the north, and it's certainly piercing (5)
I believe the answer is:
thorn
'it could veer to' is the definition.
The definition suggests a singular noun which matches the answer.
'north and it's certainly piercing' is the wordplay.
'north' anagrams to 'THORN'.
But, I'm unsure how the anagram is indicated.
'the' is the link.
Can you help me to learn more?
(Other definitions for thorn that I've seen before include "prickly type" , "quill?" , "Feature of rose tree" , "tip of R [ROSE]" , "pain in one's side" .)