Take away from daughter booklet supporting English (7)
I believe the answer is:
detract
'take away from' is the definition.
(I've seen this in another clue)
'daughter booklet supporting english' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'booklet' becomes 'tract'.
'supporting' means one lot of letters go next to another (in a down clue, some letters go below others).
'english' becomes 'e' (abbreviation).
'tract' put after 'e' is 'etract'.
'd'+'etract'='DETRACT'
(Other definitions for detract that I've seen before include "Take away (from value of something)" , "Belittle" , "Abate" , "Slight" , "Take away (from worth)" .)