In the forest wee things chirp (5)
I believe the answer is:
tweet
'chirp' is the definition.
(I know that chirp can be written as tweet)
'in the forest wee things' is the wordplay.
'in' indicates the answer is hidden within the clue.
'TWEET' is hidden in the letters of 'forest wee things'.
(Other definitions for tweet that I've seen before include "online comment" , "Sound of small bird" , "Birdsong" , "(Make a) chirping noise" , "Chirrup" .)