The 1d? (3,4,2,6)
I believe the answer is:
the back of beyond
'the 1d?' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'the 1d?' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
'1d?' could be 'd' and 'd' is located in the answer.
This explanation may well be incorrect...
(Other definitions for the back of beyond that I've seen before include "A really remote area" , "ND" , "Extremely remote place" , "most remote spot?" , "Finding this remote area might need a plan" .)