In picture in picture (7)
I believe the answer is:
imagine
'picture' is the definition.
(picture can mean to visualise or imagine)
'in picture' is the wordplay.
I cannot really see how this works, but
'in' is found in the answer.
'picture' could be 'image' (synonyms) and 'image' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for imagine that I've seen before include "Classic Lennon song" , "Fancy - Lennon song" , "Form a mental image in the mind" , "Picture in mind, envisage" , "Fancy - dream" .)