Invasive plant a gardener withdraws firstly in tall grass (7)
I believe the answer is:
ragweed
'invasive plant' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'a gardener withdraws firstly in tall grass' is the wordplay.
'firstly' indicates taking the first letters.
'in' means one lot of letters goes inside another.
'tall grass' becomes 'reed' (tall grass plant).
The initial letters of 'gardener withdraws' is 'gw'.
'a'+'gw'='agw'
'agw' inserted into 'reed' is 'RAGWEED'.
Can you help me to learn more?
(Other definitions for ragweed that I've seen before include "Unwanted plant with yellow flowers" , "bloomer" , "Plant of daisy family" , "Threat to horses" , "Allergenic plant" .)