Daisy is within my control (7)
I believe the answer is:
mastery
'control' is the definition.
(mastery is a kind of control)
'daisy is within my' is the wordplay.
'daisy' becomes 'aster' (I've seen this before).
'is within' means one lot of letters goes inside another.
'aster' put inside 'my' is 'MASTERY'.
(Other definitions for mastery that I've seen before include "Control - supreme skill" , "Total control" , "in full command" , "Comprehensive knowledge (of a subject)" , "Acquirement" .)