Youth in series nursing bust lip (9)
I believe the answer is:
stripling
'youth' is the definition.
(I've seen this before)
'series nursing bust lip' is the wordplay.
'series' becomes 'string' (sequence of similar items or events).
'nursing' is an insertion indicator.
'bust' is an anagram indicator.
'lip' is an anagram of 'ipl'.
'string' placed around 'ipl' is 'STRIPLING'.
'in' is the link.
(Other definitions for stripling that I've seen before include "youngster" , "Young 'un" , "Lad" , "Youth" , "Young boy" .)