Pleased to find Eastern forest opening (5)
I believe the answer is:
glade
'forest opening' is the definition.
(I've seen this in another clue)
'pleased to find eastern' is the wordplay.
'pleased' becomes 'glad' (similar in meaning).
'to find' means one lot of letters go next to another.
'eastern' becomes 'e'.
'glad'+'e'='GLADE'
(Other definitions for glade that I've seen before include "Forest clearing" , "wood's open space" , "Leafy clearing" , "Break in wooded area" , "Woodland clearing" .)