See age I'm in collapsing (7)
I believe the answer is:
imagine
'see' is the definition.
(I know this)
'age i'm in collapsing' is the wordplay.
'collapsing' indicates an anagram.
'age'+'im'+'in'='ageimin'
'ageimin' is an anagram of 'IMAGINE'.
(Other definitions for imagine that I've seen before include "Reckon" , "that Lennon composed" , "Picture to oneself" , "Form a mental image in the mind" , "Classic Lennon song" .)