Against type one initially agreed they pool their resources (9)
I believe the answer is:
consortia
'resources' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.
'against type one initially agreed they pool' is the wordplay.
'against' becomes 'con' (as in pros and cons).
'type' becomes 'sort' (both can mean a kind or variety).
'one initially agreed they pool' becomes 'ia' (I can't explain this - if you can you should believe this answer much more).
'con'+'sort'+'ia'='CONSORTIA'
'their' is the link.
Can you help me to learn more?
(Other definitions for consortia that I've seen before include "syndicates" , "Associations of businesses" , "Groups of bodies" , "Working associations" , "More than one commercial group" .)