Last return of Queen chap penning single (6)
I believe the answer is:
remain
'last' is the definition.
(I've seen this before)
'return of queen chap penning single' is the wordplay.
'return of' is a reversal indicator.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'chap' becomes 'man' (I've seen this before**).
'penning' means one lot of letters goes inside another.
'single' becomes 'i' (one).
'er' backwards is 're'.
'man' enclosing 'i' is 'main'.
're'+'main'='REMAIN'
(Other definitions for remain that I've seen before include "Stay on after others have gone" , "Continue in position" , "Stay, don't go" , "Stay (in position)" , "Don't leave (the EU?)" .)