Fancy a John Lennon song? (7)
I believe the answer is:
imagine
I believe this is a double definition.
'fancy' is the first definition.
(I know that fancy is a more specific form of the action imagine)
'a john lennon song?' is the second definition.
(I've seen this before)
(Other definitions for imagine that I've seen before include "John Lennon classic (just think of it!)" , "Form a mental image in the mind" , "Conceive in the mind" , "that Lennon composed" , "A Gemini? (anag)" .)