Release brick-building toy around end of August (3,2)
I believe the answer is:
let go
'release' is the definition.
(synonyms)
'brick-building toy around end of august' is the wordplay.
'brick-building toy' becomes 'lego' (toy bricks).
'around' is an insertion indicator.
'end of' says to take the final letters.
The final letter of 'august' is 't'.
'lego' going around 't' is 'LET GO'.
(Other definitions for let go that I've seen before include "Drop" , "sack" , "Don't hold on" , "Release or free" , "Set at liberty, loose grip on" .)