Herb Alpert undressed, say, when playing (7)
I believe the answer is:
parsley
'herb' is the definition.
(I know that parsley is a type of herb)
'alpert undressed say when playing' is the wordplay.
'undressed' means to look at the middle letters (the word removes the letters which clothe it).
'when playing' is an anagram indicator.
The central letters of 'alpert' are 'lper'.
'lper'+'say'='lpersay'
'lpersay' is an anagram of 'PARSLEY'.
(Other definitions for parsley that I've seen before include "Food-flavouring herb for players" , "Green plant" , "Herb with either flat or crinkly leaves" , "Cow -, fool's - and stone - are all plants" , "Herb for garnishing" .)