Stuff about English being best (5)
I believe the answer is:
cream
'being best' is the definition.
(as in 'the cream of the crop')
'stuff about english' is the wordplay.
'stuff' becomes 'cram' (synonyms).
'about' is an insertion indicator.
'english' becomes 'e' (abbreviation).
'cram' going around 'e' is 'CREAM'.
(Other definitions for cream that I've seen before include "'There are more ways of killing a cat than choking it with ....." , "Very best; pale yellow" , "Elite; colour" , "Elite; pale yellow" , "Beat" .)