Turn back and take drugs (3-3)
I believe the answer is:
dog-ear
'turn back' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'take drugs' is the wordplay.
'take' becomes 'do' (eg taking or doing drugs).
'drugs' becomes 'gear' (gear can informally mean illegal drugs).
'do'+'gear'='DOG-EAR'
'and' is the link.
Can you help me to learn more?
(Other definitions for dog-ear that I've seen before include "Hint of shabbiness" , "Turned-over page corner" , "Fold down a corner (of a page)" , "Fold on page's corner" , "Corner of a page turned down to mark your place" .)