Anticipate cheers in wood with sweetheart (9)
I believe the answer is:
foretaste
'anticipate' is the definition.
(thesaurus)
'cheers in wood with sweetheart' is the wordplay.
'cheers' becomes 'ta' (both can mean thank you).
'in' is an insertion indicator.
'wood' becomes 'forest' (synonyms).
'with' means one lot of letters go next to another.
'sweetheart' becomes 'e' (the heart/centre of 'sweet').
'ta' inserted into 'forest' is 'foretast'.
'foretast'+'e'='FORETASTE'
(Other definitions for foretaste that I've seen before include "Sample of something to come" , "Appetiser" , "Anticipation" , "Early experience" , "Preview" .)