Angry with official about new clubs forming link-up (5-9)
I believe the answer is:
cross reference
'link-up' is the definition.
(I've seen this before)
'angry with official about new clubs' is the wordplay.
'angry' becomes 'cross' (cross can mean annoyed or angry).
'with official' becomes 'referee' (referee is a kind of official. I am not sure about the 'with' bit.).
'about' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'clubs' becomes 'c' (abbreviation in card games).
'n'+'c'='nc'
'referee' placed around 'nc' is 'reference'.
'cross'+'reference'='CROSS-REFERENCE'
'forming' acts as a link.
Can you help me to learn more?
(Other definitions for cross reference that I've seen before include "Link to another part of a text" , "on one's work - it encourages one to look elsewhere" , "additional information" , "link-up" , "link to related information" .)