Swears about acquiring new pain (7)
I believe the answer is:
rawness
'pain' is the definition.
(I know that rawness is a type of pain)
'swears about acquiring new' is the wordplay.
'about' indicates an anagram.
'acquiring' indicates putting letters inside.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'swears' with letters rearranged gives 'rawess'.
'rawess' going around 'n' is 'RAWNESS'.
(Other definitions for rawness that I've seen before include "Uncooked state" , "Answers (anag)" .)