Sporting tussle that gives all-round credit (5)
I believe the answer is:
scrum
'sporting tussle' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'all-round credit' is the wordplay.
'all' becomes 'sum' (I've seen this before).
'round' is an insertion indicator.
'credit' becomes 'cr' (abbreviation).
'sum' enclosing 'cr' is 'SCRUM'.
'that gives' is the link.
Can you help me to learn more?
(Other definitions for scrum that I've seen before include "Ruck" , "crush" , "Milling crowd" , "riotous struggle" , "brawl" .)