Material on board game presented with a lot of attention (5)
I believe the answer is:
cargo
'material on board' is the definition.
'game presented with a lot of attention' is the wordplay.
'game' becomes 'go' (go is a kind of game).
'presented with' means one lot of letters go next to another.
'a lot of' means to remove the last letter (most of the word but not all of it).
'attention' becomes 'care' (I've seen this before).
'care' with its final letter taken off is 'car'.
'go' put after 'car' is 'CARGO'.
(Other definitions for cargo that I've seen before include "Payload" , "Freight, load" , "Ship's load" , "Freight on board ship" , "Goods carried by a large vehicle" .)