I really want flipping grass, teacher admitted (7)

'i really want' is the definition.
I can't judge whether this defines the answer.

'flipping grass teacher admitted' is the wordplay.
'flipping' says the letters should be written backwards.
'grass' becomes 'reed' (type of grass plant).
'teacher' becomes 'sir' (way of addressing a male teacher).
'admitted' means one lot of letters goes inside another (inserted letters get admitted).
'reed' reversed gives 'deer'.
'deer' going around 'sir' is 'DESIRER'.

Can you help me to learn more?