Our leading lady as herself: in rubber! (6)
I believe the answer is:
eraser
'rubber?' is the definition.
(rubber can mean an eraser)
'our leading lady as herself' is the wordplay.
I cannot quite see how this works, but
'as' is within the answer.
'leading lady' could be 'er' (Elizabeth Regina) and 'er' is found in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for eraser that I've seen before include "Stationery item" , "One who removed" , "Rubbing-out device" , "correction device" , "It could remove" .)