Group of players heads for large, even imposing building (6)
I believe the answer is:
castle
'imposing building' is the definition.
'castle' can be an answer for 'building' (I have seen 'Fortified building' mean 'castle' so perhaps 'building' could also mean 'castle'). I am not sure about the 'imposing' bit.
'group of players heads for large even' is the wordplay.
'group of players' becomes 'cast' (I've seen this in another clue).
'heads for' suggests taking the first letters.
The first letters of 'large even' is 'le'.
'cast'+'le'='CASTLE'
Can you help me to learn more?
(Other definitions for castle that I've seen before include "Citadel" , "Chateau" , "Fortified mansion" , "Big building" , "Dover, perhaps" .)