Be small in doorway? (5)
I believe the answer is:
exist
'be' is the definition.
(synonyms)
'small in doorway?' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'in' is an insertion indicator.
'doorway?' becomes 'exit' (I can't explain this - if you can you should believe this answer much more).
's' inserted inside 'exit' is 'EXIST'.
Can you help me to learn more?
(Other definitions for exist that I've seen before include "Scrape by" , "Subsist" , "Have being or continue living" , "Get a life!" , "Be alive" .)