Very curious about one piercing? (5)
I believe the answer is:
noisy
'piercing?' is the definition.
(thesaurus)
'very curious about one' is the wordplay.
'very curious' becomes 'nosy' (I've seen this before).
'about' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'nosy' placed around 'i' is 'NOISY'.
(Other definitions for noisy that I've seen before include "Full of disturbing sounds" , "Boisterous" , "Vociferous" , "Clamorous" , "Rowdy" .)