One chap comes up holding a ring for a girl (5)
I believe the answer is:
naomi
'girl' is the definition.
(girl's name)
'one chap comes up holding a ring' is the wordplay.
'one' becomes 'i' (Roman numeral).
'chap' becomes 'man' (chap can mean a man).
'comes up' says the letters should be written backwards (in a down clue, letters go up).
'holding' indicates putting letters inside.
'a ring' becomes 'O' (letter resembling a ring).
'i'+'man'='iman'
'iman' reversed gives 'nami'.
'nami' placed around 'o' is 'NAOMI'.
'for a' acts as a link.
(Other definitions for naomi that I've seen before include "Mother-in-law of Ruth (Bible)" , "Ruth's mother-in-law (Old Testament)" , "woman in the Bible" , "Ruth's mother-in-law (OT)" , "woman's name" .)