Engineer bore, with bit of sass, gets into bed? (7)
I believe the answer is:
retires
'gets into bed?' is the definition.
('retire' can be a synonym of 'get into bed')
'engineer bore with bit of sass' is the wordplay.
'engineer' becomes 're' (Royal Engineer).
'bore' becomes 'tire' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'bit of' says to take the initial letters.
The initial letter of 'sass' is 's'.
're'+'tire'+'s'='RETIRES'
(Other definitions for retires that I've seen before include "Gives up work" , "Withdraws" , "turns in" , "Pulls out" , "Goes to bed" .)